Description and Identification of Razorback, Flannelmouth, White

Home , Catostomus latipinnis, Mountain sucker

DESCRIPTION AND IDENTIFICATION OF

RAZORBACK, FLANNELMOUTH, WHITE, UTAH, BLUEHEAD, AND MOUNTAIN SUCKER LARVAE AND EARLY JUVENILES

STATE OF COLORADO -- DIVISION OF WILDLIFE Cover. Razorback sucker postflexion mesolarvae. About 15 mm total length, 4 weeks after hatching, and 5 weeks after fertilization. Reared at 18-19° C in March and April 1990 by the Larval Fish Laboratory from artificially fertilized eggs provided by Dexter (New Mexico) National Fish Hatchery. DESCRIPTIONS AND IDENTIFICATION OF RAZORBACK, FLANNELMOUTH, WHITE, UTAH, BLUEHEAD, AND MOUNTAIN SUCKER LARVAE AND EARLY JUVENILES

Darrel E. Snyder and Robert T. Muth

Larval Fish Laboratory Colorado State University Fort Collins, Colorado 80523

Contribution 38 of the Larval Fish Laboratory, Colorado State University

Technical Publication No. 38

Colorado Division of Wildlife

June 1990

DOW-R-T-38-90 PRICE $1.00

ISSN 0084-8883 STATE OF COLORADO Roy Romer, Governor

DEPARTMENT OF NATURAL RESOURCES Hamlet J. Barry, Executive Director

WILDLIFE COMMISSION

William R. Hegberg, Snowmass Village, Chairman; Dennis Luttrell, Divide, Vice Chairman; Eldon W. Cooper, Brighton, Secretary; Felix Chavez, Weston; Rebecca Frank, Grand Junction; Gene B. Peterson, Snyder; George VanDenBerg, Durango; Larry M. Wright, Alamosa.

DIVISION OF WILDLIFE Perry D. Olson, Director Bruce McCloskey, Deputy Director

MANAGEMENT STAFF: Bill Daley, Administrative and Technical Services; Patsy Goodman, Habitat Resources; Ed Kochman, Aquatic Resources; Len Carpenter, Terrestrial Wildlife Resources; Kris Moser, Public Services; Clyde Smith, Engineering. REGIONAL MANAGERS: Bob Caskey, Northwest; Ron Desilet, Southeast; Walt Graul, Northeast; John Torres, Central; Bob Towry, Southwest.

Edited by Nancy W. McEwen

Copies available from: Colorado Division of Wildlife, Research Center Library, 317 West Prospect, Fort Collins, CO 80526 FOREWORD

As the second decade of intensive research on rare native fishes of the Upper Colorado River Basin comes to an end, it is apparent that a complete understanding of their life histories is paramount in successful management and preservation of these unique species. To fully appreciate the ecology of any species, the ability to identify all of its life stages is essential.

These identification capabilities are especially valuable in the study of rare riverine fishes where sampling habitats and obtaining specimens can be difficult. Typically, however, availability of information on the early life of many fish species is delayed due to the tedious nature of developing taxonomic information for recently- hatched stages. This difficulty in detecting presence or absence of larval and early juvenile fish has hampered data collection on rare species such as the razorback sucker (Xyrauchen texanus).

The razorback sucker, currently listed as endangered in Colorado, is truly a unique species endemic to the Colorado River Basin. Its candidacy for federal protection under the Endangered Species Act attests to recent concern about its prospects for future survival. As a sense of urgency concerning its present abundance in the upper basin builds, the need for adequate tools to study its early-life stages is intensified.

This manual consolidates, refines, enhances, and supplements data and keys in existing publications and reports. In addition to morphological, morphometric, meristic, pigmental, and developmental state characters, it incorporates selected skeletal characters to help distinguish larval and early juvenile fishes. The keys and descriptive accounts are the most definitive prepared to date for early-life stages of catostomids occurring in the Upper Colorado River Basin. This work will prove invaluable as we enter the third decade of research on riverine fish communities of the upper basin. --, z._ i s' dae,e

Patrick J. Martinez Wildlife Biologist

DEDICATION We dedicate this publication to

Carroll Lynn Bjork

whose drawings have been the heart of descriptions emanating from the Larval Fish Laboratory.

iii CONTENTS

ABSTRACT ...... 1 RESULTS AND CONCLUSIONS ...... 23 Comparative Summary ...... 23 Size relative to state of development INTRODUCTION ...... 2 23 Meristics and morphometrics ...... 24 Pigmentation ...... 27 A COMBINED DEVELOPMENTAL Mouth characters ...... 31 INTERVAL TERMINOLOGY ...... 5 Osteological features ...... 32 Keys ...... 37 Eggs ...... CHARAC,1ERISTICS USEFUL IN 39 IDENTIFICATION OF CYPRINIFORM Protolarvae ...... 39 FISH LARVAE ...... 7 Flexion Mesolarvae ...... 47 Postflexion Mesolarvae ...... 54 Myomeres ...... 9 Skeletal Character Key ...... 73 Fins and Finfolds ...... 10 Metalarvae ...... 73 Other Countable Structures ...... 12 Skeletal Character Key ...... 81 Morphology ...... 12 Juveniles ...... 82 Pigmentation ...... 13 Skeletal Character Key ...... 98 Osteology ...... 14 Species Accounts — Catostomus ardens ...... 100 SPECIMENS EXAMINED ...... 15 Catostomus commersoni ...... 108 Catostomus discobolus ...... 116 Catostomus latipinnis ...... 124 METHODS ...... 16 Catostomus platyrhynchus ...... 132 Xyrauchen texanus ...... 140 Specimen Data and Observations ...... 16 Clearing and Staining Procedure ...... 19 LITERATURE CITED ...... 148

TABLES

Number Page Number Page

1 Comparison of size at onset or 12 Dimensions of frontoparietal transition of developmental events . . 24 fontanelle for Catostomus ardens . . . 107 2 Comparison of the more diagnostic 13 Selected juvenile and adult meristics differences in meristics ...... 25 for Catostomus commersoni ...... 108 Comparison of the more diagnostic 3 14 Size at apparent onset of selected differences in morphometrics ...... 26 developmental events for Catostomus 4 Comparison of size relative to commersoni ...... 108 state of peritoneum ...... pigmental 28 15 Size at developmental interval and gut 5 Comparison of the more diagnostic phase transitions for Catostomus melanophore pigmentation patterns . . 29 commersoni ...... Comparison of size relative to mouth 109 6 Summary of and position and lower lip lobe separation 32 16 morphometrics Comparison of myomere counts for Catostomus 7 frontoparietal commersoni ...... fontanelle size ...... 33 109 8 Selected juvenile and adult meristics 17 Dimensions of frontoparietal fontanelle for Catostomus commersoni ...... for Catostomus ardens ...... 100 115 9 Size at apparent onset of selected 18 Selected juvenile and adult meristics developmental events for Catostomus for Catostomus discobolus ...... 116 ardens ...... 100 19 Size at apparent onset of selected 10 Size at developmental interval and gut developmental events for Catostomus phase transitions for Catostomus discobolus ...... 116 ardens ...... 101 20 Size at developmental interval and gut 11 Summary of morphometrics and phase transitions for Catostotnus myomere counts for Catostomus ardens 101 discobolus ...... 117

iv TABLES (continued)

Number Page Number Page

21 Summary of morphometrics and 30 Size at developmental interval and myomere counts for Catostomus gut phase transitions for discobolus ...... 117 Catostomus platyrhynchus ...... 133 22 Dimensions of frontoparietal 31 Summary of morphometrics and fontanelle for Catostomus discobolus 123 myomere counts for Catostomus 23 Selected juvenile and adult meristics platyrhynchus ...... 133 for Catostomus latipinnis ...... 124 32 Dimensions of frontoparietal 24 Size at apparent onset of selected fontanelle for Catostomus developmental events for Catostomus platyrhynchus ...... 139 latipinnis ...... 124 33 Selected juvenile and adult meristics 25 Size at developmental interval for Xyrauchen texanus ...... 140 and gut phase transitions for Catostomus ladpinnis ...... 34 Size at apparent onset of selected 125 developmental events for Xyrauchen 26 Summary of morphometrics and texanus ...... myomere counts for Catostomus 140 latipinnis ...... 125 35 Size at developmental interval and 27 Dimensions of frontoparietal gut phase transitions for Xyrauchen fontanelle for Catostomus latipinnis . 131 texanus ...... 141 28 Selected juvenile and adult meristics 36 Summary of morphometrics and for Catostomus platyrhynchus ...... 132 myomere counts for Xyrauchen 29 Size at apparent onset of selected texanus ...... 141 developmental events for Catostomus 37 Dimensions of frontoparietal platyrhynchus ...... 132 fontanelle for Xyrauchen texanus . . 147

FIGURES

Number Page Number Page 1 The Upper Colorado River System . 4 17 Catostomus ardens postflexion 2 Selected anatomical features of mesolarva ...... 103 catostomid fish eggs and embryos ...... 7 18 Catostomus ardens metalarva, 3 Selected anatomical features of recently transformed ...... 104 catostomid fish larvae ...... 8 19 Catostomus ardens metalarva ...... 104 4 Measures and counts for larval and 20 Catostomus ardens juvenile, early juvenile fishes ...... 17 recently transformed ...... 105 5 Phases of gut coil development in 21 Catostomus ardens juvenile ...... 105 catostomid fish larvae and early 22 Selected diagnostic skeletal features juveniles ...... 18 of metalarval Catostomus ardens . . . 106 6 Location of selected skeletal features 19 23 Selected diagnostic skeletal features 7 Frontoparietal fontanelles of early of early-juvenile Catostomus ardens . 106 juveniles ...... 34 24 Interneurals of larval and early 8 Interneurals of late metalarvae ...... 34 juvenile Catostomus ardens ...... 107 9 Position of mandibles relative to 25 Frontoparietal fontanelle of maxillae of late metalarvae ...... 35 metalarval and early juvenile 10 Anterior-dorsal maxillary projections Catostomus ardens ...... 107 of late metalarvae ...... 35 26 Catostomus commersoni adult ...... 108 11 Postcleithra of late metalarvae ...... 36 27 Regional distribution of Catostomus 12 Catostomus ardens adult ...... 100 commersoni ...... 108 13 Regional distribution of Catostomus 28 Catostomus commersoni protolarva, ardens ...... 100 recently hatched ...... 110 14 Catostomus ardens protolarva, 29 Catostomus commersoni protolarva . . 110 recently hatched ...... 102 30 Catostomus commersoni flexion 15 Catostomus ardens protolarva ...... 102 mesolarva, recently transformed ...... 111 16 Catostomus ardens flexion 31 Catostomus commersoni postflodon mesolarva, recently transformed ...... 103 mesolarve ...... 111 FIGURES (continued)

Number Page Number Page

32 Catostomus commersoni metalarva, ...... 65 Selected diagnostic skeletal features recently transformed ...... 112 of early-juvenile Catostomus latipinnis 130 33 Catostomus commersoni metalarva . . 112...... 66 Interneurals of larval and early 34 Catostomus commersoni juvenile, juvenile Catostomus latipinnis ...... 131 67 Frontoparietal fontanelle of recently transformed ...... 113...... 35 Catostomus commersoni juvenile ...... 113 metalarval and early juvenile 36 Selected diagnostic skeletal features of Catostomus latipinnis ...... 131 metalarval Catostomus commersoni . . . 114 68 Catostomus platyrhynchus adult ...... 132 69 Regional distribution of Catostomus 37 Selected diagnostic skeletal features of ...... early-juvenile Catostomus commersoni 114 platyrhynchus ...... 132 70 Catostomus platyrhynchus protolarva, 38 Interneurals of larval and early ...... juvenile Catostomus commersoni ...... 115 recently hatched ...... 134 39 Frontoparietal fontanelle of 71 Catostomus platyrhynchus protolarva . 134 Catostomus platyrhynchus metalarval and early juvenile ...... 72 flexion Catostomus commersoni ...... 115 mesolarva, recently transformed ...... 135 40 Catostomus discobolus adult ...... 116...... 73 Catostomus platyrhynchus postflexion 41 Regional distribution of Catostomus mesolarva ...... 135 discobolus ...... 116...... 74 Catostomus platyrhynchus metalarva, 42 Catostomus discobolus protolarva, recently transformed ...... 136 recently hatched ...... 118...... 75 Catostomus platyrhynchus metalarva . 136 43 Catostomus discobolus protolarva . . . 118...... 76 Catostomus platyrhynchus juvenile, 44 Catostomus discobolus flexion recently transformed ...... 137 mesolarva, recently transformed ...... 119...... 77 Catostomus platyrhynchus juvenile . . . 137 45 Catostomus discobolus postflexion ...... 78 Selected diagnostic skeletal mesolarva ...... 119 features of metalarval Catostomus 46 Catostomus discobolus metalarva, platyrhynchus ...... 138 recently transformed ...... 120...... 79 Selected diagnostic skeletal features ...... 47 Catostomus discobolus metalarva . . . 120 of early-juvenile Catostomus 48 Catostomus discobolus juvenile, platyrhynchus ...... 138 recently transformed ...... 121...... 80 Interneurals of larval and early 49 Catostomus discobolus juvenile ...... 121 juvenile Catostomus platyrhynchus . . . 139 50 Selected diagnostic skeletal features 81 Frontoparietal fontanelle of of metalarval Catostomus discobolus . . 122 metalarval and early juvenile 51 Selected diagnostic skeletal features of Catostomus platyrhynchus ...... 139 early-juvenile Catostomus discobolus . 122...... 82 Xyrauchen texanus adult ...... 140 52 Interneurals of larval and early ...... 83 Regional distribution of Xyrauchen juvenile Catostomus discobolus ...... 123 reran us ...... 140 53 Frontoparietal fontanelle of 84 Xyrauchen texanus protolarva, metalarval and early juvenile recently hatched ...... 142 Catostomus discobolus ...... 123...... 85 Xyrauchen texanus protolarva ...... 142 54 Catostomus latipinnis adult ...... 124...... 86 Xyrauchen texanus flexion mesolarva, 55 Regional distribution of Catostomus recently transformed ...... 143 latipinnis ...... 124...... 87 Xyrauchen texanus postflexion 56 Catostomus latipinnis protolarva, mesolarva ...... 143 126...... 88 recently hatched ...... Xyrauchen texanus metalarva, 57 Catostomus latipinnis protolarva ...... 126 recently transformed ...... 144 58 Catostomus latipinnis flexion 89 Xyrauchen texanus metalarva ...... 144 mesolarva, recently transformed ...... 127...... 90 Xyrauchen texanus juvenile, 59 Catostomus latipinnis postflexion recently transformed ...... 145 mesolarva ...... 127...... 91 Xyrauchen texanus juvenile ...... 145 60 Catostomus latipinnis metalarva, 92 ...... Selected diagnostic skeletal features recently transformed ...... 128 of metalarval Xyrauchen texanus ...... 146 61 Catostomus latipinnis metalarva ...... 128...... 93 Selected diagnostic skeletal features 62 Catostomus latipinnis juvenile, of early-juvenile Xyrauchen texanus . 146 recently transformed ...... 129...... 94 Interneurals of larval and early 63 Catostomus latipinnis juvenile ...... 129 juvenile Xyrauchen texanus ...... 147 64 Selected diagnostic skeletal features 95 Frontoparietal fontanelle of metalarval of metalarval Catostomus latipinnis . . . 130 and early juvenile Xyrauchen ternnus . 147

vi ACKNOWLEDGMENTS

This publication is the culmination of nearly a decade of work on early life stages of the species covered. It builds upon descriptions and preliminary keys previously sponsored by the Bureau of Land Management (United States, Colorado Office), Colorado Division of Wildlife (former Non-Game Section), Colorado State University Experiment Station, Ecosystem Research Institute (Logan, Utah), United States Fish and Wildlife Service (Colorado River Fishery Project and Reno Fisheries Assistance Office), and Utah Division of Wildlife Resources. Some text and data, and many illustrations were originally published in Snyder (1981, 1983a) and Snyder and Muth (1988).

Developmental studies at the Larval Fish Laboratory have depended on the assistance and cooperation of many individuals, including Colorado State University (CSU) students serving as Larval Fish Laboratory volunteers or employees. Edmund Wick was responsible for obtaining fertilized eggs and rearing developmental study series of many of the species studied. Mark Castagneri, Al Davis, Gary Dean, Carol Jefferson, Philip Harrison, David Herbet, Jeff Pearson, Dale Brown, and Keith Fulsos (Brown and Fulsos via summer CETA Youth Program) assisted with culture or organization of collected specimens for study. James Barrowman, Lynn Bjork, William Emerson, Lyndon Evans, Stephanie Salyer, and Edmund Wick assisted with acquisition of morphometric and meristic data from hundreds of specimens. Timothy Hill, Jack Piccolo, and Steven Platania cleared and stained some specimens. Steve Meismer, Jack Ruppert, and Mark Williams assisted with editing of the keys.

Additional specimens were donated by or borrowed from William Hauser (Alaska Department of Fish and Game, Anchorage), Philip Harrison (CSU), Arizona State University Center for Environmental Studies (Tempe, via Daniel Langhorst and Paul Marsh), Bio/West Inc. (Logan, Utah, via Paul Holden), Ecosystem Research Institute (Logan, Utah, via Richard Valdez and John Carter), Utah Cooperative Fish and Wildlife Research Unit (Utah State University, Logan, via Timothy Modde and Neal Muirhead), Utah Division of Wildlife Resources (Salt Lake City, via Randy Radant and Dennis Shirley), and United States Fish and Wildlife Service: Colorado River Fish Project (Grand Junction, Colorado, and Vernal, Utah, via Lynn Kaeding and Harold Tyus), Fisheries Assistance Office (Reno, Nevada via Donald King and Gary Scoppetone), and Dexter National Fish Hatchery (New Mexico, via Roger Hamman). Parental stock for white sucker culture was obtained from a local pond owned by Louis Swift.

C. Lynn Bjork prepared original and all previously published drawings except as follows. Selected drawings of Catostomus commersoni larvae were reproduced with permission from Stewart (1926), Buynak and Mohr (1978), and Fuiman (1979, drawings by C. Komar Outlaw). Drawings of adult suckers were reproduced with permission from Miller (1952, drawings by William Brudon) and Behnke and Benson (1983, drawing by Doris Rust).

Colorado Division of Wildlife contract supervisors Patrick Martinez and Thomas Nesler were extremely patient with our many delays and revisions. Anita Martinez, Kenneth Tiffan, Maryann Snyder and Clarence Carlson reviewed draft manuscripts. Kevin Bestgen scrutinized near final versions of the keys.

Facilities and secretarial support were provided by the Department of Fishery and Wildlife Biology, College of Forestry and Natural Resources, CSU. Michael Dallwitz of CSIRO Division of Entomology in Canberra, Australia, provided copies of DELTA system computer programs and manuals to aid key production. This manual was sponsored by the Colorado Division of Wildlife, Endangered Fishes Investigations SE-3 and the U.S. Fish and Wildlife Service, Division of Federal Aid.

vii Frontispiece. Yearling razorback suckers. Top -- interneural bones of cleared and stained specimen, 65 mm total length. Bottom -- predorsal keel barely evident immediately behind the head of a living specimen, 85 mm total length. Reared by the Larval Fish Laboratory from eggs artificially fertilized on June 8, 1980, from adults collected in gravel pits connected to the Colorado River near Clifton, Colorado. DESCRIPTIONS AND IDENTIFICATION OF RAZORBACK, FLANNELMOUTH, WHITE, UTAH, BLUEHEAD, AND MOUNTAIN SUCKER LARVAE AND EARLY JUVENILES

ABSTRACT

Larvae of the endangered razorback sucker (Xyrauchen texanus) and six other suckers (genus Catostomus) in the Upper Colorado River System are broadly similar in appearance. To facilitate identification, developmental series of all species except longnose sucker (C. catostomus) were studied for differences in morphology, meristics, pigmentation, size relative to developmental state, and skeletal features. The razorback sucker is most similar to bluehead sucker (C. discobolus) as protolarvae and flexion mesolarvae and flannelmouth sucker (C. latipinnis) as metalarvae and early juveniles. Some razorback sucker larvae can be distinguished by early yolk absorption, early scattering of dorsal pigmentation, few or no melanophores along the ventral mid-line between heart and vent, and generally lighter or less widely distributed body pigmentation. Later larvae and juveniles can be distinguished by 14 or more dorsal fin rays; a correspondingly long dorsal fin base; a large, fan-shaped, first interneural bone; and a large, oval-shaped, frontoparietal fontanelle. Bluehead sucker and mountain sucker (C. platyrhynchus) represent subgenus Pantosteus and are best characterized by early scattering of dorsal pigmentation; early folding of the gut; dark peritoneum; a generally smaller dorsal fin; a small, blocky, first interneural bone; a narrow fontanelle; and, for early juveniles, a distinctive mouth. The midventral line of pigment from heart to vent is often complete for mountain sucker larvae and highly variable for bluehead sucker larvae. The remaining species represent subgenus Catostomus. Flannelmouth sucker are distinguished by their large size at hatching, yolk absorption, and onset of other developmental events; also by delayed gut folding, generally lighter or less widely distributed body pigmentation, limited midventral pigmentation, distinctive "tractor-tread" pigment pattern on the dorsum of some mesolarvae, and very small scales in juveniles. A complete midventral line of melanophores from the heart or branchial region to vent is typical of white sucker (C. commersoni) larvae while large scales, frequently well outlined with pigment, and a series of three large lateral spots characterize larger young-of-the-year juveniles. Utah sucker (C. ardens) usually have larger eyes relative to head length than the other species. They are similar to white sucker, but larvae usually have much less midventral pigmentation, sometimes none, and juveniles have only two, if any, prominent lateral spots.

1 INTRODUCTION

Despite the information explosion and labor of love" on the part of the researchers technological advances of the past few involved. decades, knowledge of the biology of many North American fishes remains inadequate Of approximately 775 species of fresh- for either evaluation of potential environ- water and anadromous fishes in North Amer- mental impacts on aquatic ecosystems or ica (Lee et al. 1980), less than 20% are ade- optimal management of fisheries. Knowledge quately described as larvae for identification of early-life stages (eggs, larvae, and early purposes (extrapolated from 15% reported by juveniles) is especially weak. For most spe- Snyder 1976a). In a relatively comprehensive cies, the larvae and early juveniles represent listing of regional guides, keys, and compar- several life-intervals that are ecologically ative descriptions of larval fishes by Simon distinct from each other and from their later (1986), only about 80 of 230 citations (35%) juvenile and adult counterparts. Knowledge pertain to freshwater species. Snyder (1983b) of habitat requirements and limitations, popu- listed 11 regionally oriented larval fish identi- lation dynamics, and behavior of these early- fication manuals for or including freshwater life intervals will improve our understanding species (some of these are for the same of aquatic ecosystems and communities and regions and all are incomplete in coverage). facilitate more effective monitoring and Since 1983 five local or regional guides for management of fish populations and habitats. freshwater larvae have been published Such knowledge is particularly valuable in (Conrow and Zale 1985, McGowan 1984 and evaluation of environmental impacts and 1988, Sturm 1988, and Wang 1986). recovery of endangered species such as the The purpose of this publication is to razorback sucker (Xyrauchen texanus). facilitate identification of larval and early- Early-life stages of fishes are or should juvenile razorback, flannelmouth, bluehead, be a principal focus of many ecological stud- mountain, white, and Utah suckers (Xyrau- ies (Snyder 1976a). Their distributions and chen texanus, Catostomus latipinnis, C. disco- densities are indicative of spawning and nur- bolus, C. platyrhynchus, C. commersoni, and sery areas, spawning seasons, larval behavior, C. ardens respectively). All but Utah sucker and year-class strength. Even in baseline are covered to some degree in the metalarva surveys designed to determine presence and key and descriptions by Snyder (1981), a relative abundance of fishes, larval collections mountain sucker description by Snyder can often provide information on certain spe- (1983a) and in an unpublished provisional key cies that because of gear selectivity, behavior, to protolarvae and mesolarvae Snyder pre- or habitat are difficult to collect or observe as pared in 1984 for the Colorado Division of adults. Studies of fish larvae also can provide Wildlife and Ecosystems Research Institute information on morphological development, of Logan, Utah. However, except for flannel- systematics, growth rates, survival rates, food mouth sucker, species accounts in the 1981 habits, predation, and various other ecological publication are incomplete and previously relationships. prepared keys are tentative and based on limited descriptive information. By compar- Research on ecology of early-life stages ison, species accounts and keys in this manual and subsequent management efforts depend are much more comprehensive for the char- on accurate identification of collected speci- acters studied and the accounts include full mens. Inland fishery managers and research- sets of three-view illustrations for all but ers often exclude potentially critical larval- white sucker. Species accounts for mountain fish investigations specifically because they and Utah suckers are modifications of those "haven't done it before" or they don't have in Snyder and Muth (1988). the taxonomic tools needed for the job. Unfortunately, acquisition of this vital taxo- The early-life stages of white sucker have nomic information is very time-consuming been described or included in identification and expensive. While such information is manuals by many other authors: Crawford slowly building, the many individual efforts (1923), Stewart (1926), Fish (1929,1932), are piecemeal, uncoordinated, and often "a Mansueti and Hardy (1967), Lippson and

2 Moran (1974), Long and Ballard (1976), catostomus), was described by Fuiman and Buynak and Mohr (1978), Jones et al. (1978), Witman (1979) and included in the Great Loos et al. (1978), Fuiman (1978, 1979), Lakes manual edited by Auer (1982). All Wang and Kernehan (1979), McElman and seven species belong to the subfamily Catos- Balon (1980), and Auer (1982). The pattern tominae and tribe Catostomini. Xyrauchen is of three large lateral spots typical of early a monotypic genus. Among the Catostomus juvenile white suckers was recognized at least species, the bluehead and mountain suckers as early as Ellis (1914). Although Metcalf represent a distinctive group known as (1966) suggested that there is little rationale "mountain suckers," subgenus Pantosteus; the for subspecies designations (e.g., C. commer- others represent "valley suckers," subgenus soni suckeyi for western white sucker), diag- Catostomus (Smith 1987). nostic comparisons of larvae herein are based on data from western populations rather than The biology and distribution of fishes in previous white sucker descriptions from east- the Upper Colorado River System (Fig. 1) ern populations. was most recently reviewed by Behnke et al. (1982), Carlson and Carlson (1982), Miller et Winn and Miller (1954) included meso- al. (1982a), Tyus et al. (1982), Woodling larvae of razorback sucker, flannelmouth suc- (1985), and Carlson and Muth (1989). ker, and Pantosteus species in their photo- Razorback, flannelmouth, bluehead, and graph-illustrated key. All Pantosteus larvae mountain suckers are native to the System. included in that publication have since been The razorback sucker is protected by Colo- recognized as desert sucker (Catostomus rado and Utah and has long been a candidate clarki) by Smith (1966). Pigmentation of for the federal threatened and endangered bluehead and mountain sucker mesolarvae is species list. Flannelmouth and bluehead typically similar to that documented by Winn suckers are common to abundant in main- and Miller for desert sucker. However, pig- stem rivers throughout the System. The mental variation is much greater and for white sucker is present but less abundant in bluehead and mountain suckers of similar the Colorado, Gunnison, Yampa, and upper size dorsal and lateral pigmentation can be Green Rivers. The mountain sucker is res- indistinguishable from that illustrated and tricted largely to headwater tributaries described by Winn and Miller for razorback throughout much of the Green River Sub- sucker. basin and is rarely found in mainstem rivers. In the process of documenting hybridiza- However, individual specimens have been tion among several species of suckers, Hubbs reported in the Green River near the con- et al. (1943) described young-of-the-year fluence with the Yampa River and in the juveniles (and commented on some larvae) White River near and above the confluence of flannelmouth, white, bluehead, and moun- with Piceance Creek. The Utah sucker is tain suckers. Hubbs and Hubbs (1947) did restricted largely to headwater tributaries the same for flannelmouth and bluehead suc- west of the Green River, particularly the kers. Douglas (1952) published a photograph Duchesne River. A few specimens have been of a razorback sucker protolarva (or recently reported in the Green River in or below the transformed mesolarva) without yolk. Doug- lower end of Dinosaur National Monument. las's publication also included a photograph The longnose sucker (C. catostomus) is found of a 10 cm specimen which, as noted by Winn only above Flaming Gorge Reservoir, in the and Miller (1954), is not a juvenile razorback Blue Mesa area of the Gunnison River, and sucker but rather an adult speckled dace in the Lake Granby area of the Colorado (Rhinichthys osculus). Minckley and Gustaf- River. son (1982) chronicled the early development The distribution and ecology of sucker of the razorback sucker but their illustrations larvae and young-of-the-year juveniles in the of larvae are poor and misleading. Mountain Upper Colorado River System has not yet and Utah sucker larvae have not been des- been summarized, but selected information cribed by authors other than ourselves. can be found in various progress reports, final This publication covers six of seven reports, and formal publications by regional species of Catostomidae inhabiting the Upper researchers (e.g., Carlson et al. 1979, Miller Colorado River System. The species not et al. 1982b, Haynes et al. 1985, and Tyus et covered herein, the longnose sucker (C. al. 1987).

3 112° 110° 108° 106°

42° 42°

Flaming Gorge Res. WYOMING UTAH COLORADO

DUCHESNE R.

40° 40°

.64>0

SA 4).

GuivivisoAl

0 0 < 4- 13 38° 38° 4A. IP mi "vT 0 50 100

Lake 0 50 100 150 Powell km

ARIZONA NEW MEXICO

112° 110° 108° 106°

Fig. 1. The Upper Colorado River System.

4 A COMBINED DEVELOPMENTAL INTERVAL TERMINOLOGY

It is often convenient and desirable to grates principal subdivisions and functions of divide the ontogeny of fish into specifically the three component terminologies. In doing defmed intervals. If the intervals selected are so, Ahlstrom's "preflexion-flexion-postflexion" used by many biologists as a frame of refer- terminology is treated, for fishes with homo- ence, such division can facilitate communica- cercal tails, as a subset of Snyder's mesolarva tion and comparison of independent results. phase. Since notochord flexion in the caudal The largest intervals, periods (e.g., embry- region usually begins when the first caudal fm onic, larval, juvenile, and adult), are often rays appear and is essentially complete when sub-divided into phases and sometimes into all principal caudal fm rays are well defmed, steps (Balon 1975b and 1984); the word and since presence of fm rays can be more "stage," although commonly used as a syno- precisely observed than the beginning or end nym for period or phase (e.g., Kendall et al. of actual notochord flexion, fm rays are used 1984), should be reserved for instantaneous as transition criteria. As a result, all proto- states of development. larvae are preflexion larvae, and all metalarvae are postflexion larvae. Although most The larval phase terminologies most fish pass sequentially through all phase sub- commonly used in recent years, particularly divisions designated, some pass pertinent for descriptive purposes, are those defined by points of transition prior to hatching or birth Hardy et al. (1978 -- yolk-sac larva, larva, and begin the larval period in a later phase or prejuvenile; modified from Mansueti and possibly skip the period entirely. Hardy 1967), Ahlstrom et al. (1976 -- preflexion, flexion, postflexion; expanded upon by The definition for the end of the larval Kendall et al. 1984), and Snyder (1976b and period is necessarily a compromise deleting 1981 -- protolarva, mesolarva, metalarva). all requirements (some taxon-specific, others Definitions for all three terminologies were difficult to determine precisely) except acqui- presented by Snyder (1983b). During a work- sition of the full complement of fin spines shop on standardization of such terminolo- and rays in all fins and loss of all finfold (last gies, held as part of the Seventh Annual remnants are usually part of the preanal fm- Larval Fish Conference (Colorado State Uni- fold). Provision for taxon-specific prejuvenile versity, January 16, 1983), it became obvious (or transitional) phases are also deleted. In that these are not competing terminologies, some cases, finfold persists through the end- as they often are treated, but rather comple- point for such special intervals, and the inter- mentary options with subdivisions or phases vals are effectively included in the larval defined for different purposes. As such, it is period. possible to utilize all three terminologies simultaneously to: (1) facilitate comparative Timing of complete yolk absorption varies from well before notochord flexion and descriptions and preparation of keys based on initial fin ray formation, as in most fishes with fish in similar states of development with res- pelagic larvae, to postflexion stages after all pect to morphogenesis of finfold and fins; (2) or most of the fin rays are formed, as in segregate, for fishes with homocercal tails, many salmonids. Accordingly, the interval morphometric data based on standard lengths during which fish larvae bear yolk should not measured to the end of the notochord prior be represented generally as a separate phase to and during notochord flexion from those preceding phases based on fin formation as it measured to posterior margin of the hypural has been treated by Kendall et al. (1984). plates following notochord flexion; and (3) The Hardy et al. terminology effectively dis- approximate transition from at least partially tinguishes between larvae with and without endogenous nutrition (utilization of yolk yolk by modifying the period name with the material) to fully exogenous nutrition (depen- adjective "yolk-sac" when yolk material is dence on ingested food) based on presence or present. Any period or phase name of the absence of yolk material. combined terminology can be similarly modi- The combined terminology presented fied to indicate presence or absence of yolk below and utilized herein effectively inte- material (e.g., yolk-bearing larva, yolk-sac

5 metalarva, postfleadon mesolarva with yolk, example, if it is necessary to acknowledge protolarva without yolk). only that the fish is a larva and whether it The combined terminology is designed to bears yolk, the terms "yolk-sac larva" and be relatively simple but comprehensive, pre- "larva without yolk" are all that is needed. cise in its transition criteria, applicable to Biologists who formerly utilized one of its nearly all teleost fishes, and flexible. It can component terminologies should have no be utilized in part (essentially as one of its difficulty in adapting to the combined component terminologies) or its entirety terminology -- essential features and terms of depending on purposes of the user. For the original terminologies have been retained.

Larva: Period of fish development between hatching or birth and (1) acquisition of adult complement of fin spines and rays (principal and rudimentary) in all fins, and (2) loss beyond recognition of all finfold not retained by the adult.

Protolarva: Phase of larval development characterized by absence of dorsal, anal, and caudal fin spines and rays. (Standard length measured to end of notochord.)

Mesolarva: Phase of larval development characterized by presence of at least one dorsal, anal, or caudal fin spine or ray but either lacking adult complement of principal soft rays in all median (dorsal, anal, and caudal) fills or lacking pelvic fm buds or fins (if present in adult). (Standard length measured to end of notochord or, when sufficiently developed, axial skeleton.)

Preflexion Mesolarva: Among fishes with homocercal tails, phase of mesolarval development characterized by absence of caudal fin rays. (Posterior portion of notochord remains essentially straight and standard length measured to end of notochord. When first median fin ray is a caudal ray, as in most fishes, larva progresses directly from protolarva to flexion mesolarva.)

Flexion Mesolarva: Among fishes with homocercal tails, phase of mesolarval development characterized by an incomplete adult complement of principal caudal fin rays. (Posterior portion of notochord flexes upward and standard length measured to end of notochord.)

Postflexion Mesolarva: Among fishes with homocercal tails, phase of mesolarval development characterized by adult complement of principal caudal fm rays. (Notochord flexion essentially complete and standard length measured to posterior-most margin of hypural elements or plates.)

Metalarva: Phase of larval development characterized by presence of (1) adult complement of principal soft rays in all median fins and (2) pelvic fin buds or fins (if present in adult). (Standard length measured to posterior end of axial skeleton, hypural elements or plates in fishes with homocercal tails.)

Yolk-sac, Yolk-bearing, With Yolk, Without Yolk: Examples of modifiers used with any of the above period or phase designations to indicate presence or absence of yolk material, including oil globules.

6 CHARACTERISTICS USEFUL IN IDENTIFICATION OF CYPRINIFORM FISH LARVAE

The following discussion of taxonomically ation of a single specimen, the number of useful characters is reprinted with minor candidate species can be substantially reduced modification from Snyder (1981) and Snyder by a list of known or likely species based on and Muth (1988). Fishes of the families adult captures in the study area or connected Cyprinidae (minnows and carps) and Catosto- waters. However, there are cases in which midae (suckers) are closely related and mor- the presence of certain species was first docu- phologically similar. Together the two fami- mented by collection and identification of lar- lies account for nearly half of over 50 species vae. Incidental transport of eggs or larvae in the Upper Colorado River System. Gener- from far upstream or distant tributaries also alizations with respect to the order Cyprin- must be considered. Knowledge of spawning iformes refer specifically to North American seasons, temperatures, habitats, and behavior species of these families. Figures 2 and 3 coupled with information on egg deposition, identify the more obvious morphological larval nursery grounds, and larval behavior features and structures of catostomid (and are also useful in limiting possibilities. cyprinid) eggs and larvae. Berry and Richards (1973) noted that Identification of fish larvae is in part a "although species of a genus may vary from process of elimination. Even before examin- one geographical area to another, generally

Chorion Embryonic Shield Blastomeres Axial Strand (best seen Yolk from above) Pen blast Yolk under Corona thin yolk-sac with cavity Perivitelline between Space Germ Ring Yolk protruding EARLY CLEAVAGE MORULA through Germ Ring GASTRULA

Otic Vesicle Axial Strand Optic Vesicle Somite Mesoderm Pharynx Segment Crest of Head Mass Mesoderm Lens Intermediate Mesoderm Yolk-sac Cavity Mesodermal Areola Yolk under Yolk-sac Yolk Plug with protruding Periblast Trunk-tail Material Mound Bud EARLY EMBRYOS

Fig. 2. Selected anatomical features of cypriniform fish eggs and embryos (from Snyder 1981; based on drawings from Long and Ballard 1976).

7 Fig. PROTOLARVA 3. Selected anatomicalfeaturesof cypriniform fishlarvae(fromSnyder1981). Lower orMandibularJaw Region ofFore-,Mid-, Pericardial Cavity Pectoral FinBud Pectoral Fin Pelvic FinBud Lens ofEye Stomach Region Otolith Choroid FissureofEye Upper orMaxillaryJaw Nares Heart Heart Region Melanophore Preanal Finfold Olfactory Placode Opercle Auditory (Otic)Vessicle Clithrum No Horizontal Skeletogenous Gill Coiled orFoldedGut Urogenetal Myosepta Myomere Gas (Air)Bladder Dorsal Fin Caudal Fin Median Finfold Yolk withinYolk-sac Vent (Anus) Rudimentary Rays Pterygiophore Principal Rays and Hindbrain Rudimentary Ray Septa Principal Rays Upturned Notochordand Hypurals ofLowerPlate Upper Hypural Dorsal Portion Ventral Portion Primordia Analage ofUrostyle

Duct Pigment 8 (exposed) Plate

ME S OL AR VA the larval forms of closely related species mesolarvae. They begin as part of the look alike. At the same time, larvae of dis- embryonic somites and are usually formed in tantly related forms may be closely similar in their full complement prior to hatching. gross appearance." Cypriniform larvae as a Throughout the protolarval and much of the group are distinctive and generally easy to mesolarval phase, myomeres are chevron- distinguish from larvae of other families. shaped, but by the metalarval phase they Beginning workers should become familiar evolve to their typical three-angled adult with the general larval characteristics of each form. Fish (1932) and many subsequent family likely to be encountered. The guides authors observed that there is a nearly direct, and keys cited in Snyder (1983b) are most one-to-one correlation between total myo- useful in this respect. Auer (1982) is parti- meres and total vertebrae (including Weber- cularly recommended since it covers all fami- ian ossicles in cypriniforms). Snyder (1979) lies and some species in the Upper Colorado and Conner et al. (1980) summarized myo- River Basin. Discussions of taxonomic char- mere and vertebral counts for many cyprin- acters by Berry and Richards (1973) and iform fishes. Kendall et al. (1984) are also recommended. The most anterior and most posterior In the Upper Colorado River System, myomeres are frequently difficult to dis- cypriniform larvae are readily categorized as tinguish. The most anterior myomeres are cyprinids or catostomids. But elsewhere, if apparent only in the epaxial or dorsal half of members of the cyprinid subfamily Cyprini- the body; the first is often deltoid in shape nae (carps) and the catostomid subfamily and is located immediately behind the occi- Ictiobinae (carpsuckers and buffalofishes) or put. The most posterior myomere is defmed tribe Erimyzontini (chubsuckers) are present, as lying anterior to the most posterior com- identification at the family level can be more plete myoseptum. Siefert (1969) describes a difficult. "false (partial) myoseptum" posterior to the Within their respective families, and last complete myoseptum which adds to the especially at the subfamily level, cypriniform difficulty of discerning the last myomere. larvae are very homogeneous in gross struc- Early in the larval period, myomeres are most ture and appearance. Accordingly, they may readily observed using transmitted light. be especially difficult to discriminate at genus Polarizing filters, depending on thickness and or species levels. This is particularly true of certain other qualities of the preserved Colorado River System suckers. For the tissues, can dramatically increase contrast latter, specific identification relies on size at between the muscle tissue of myomeres and which certain developmental events occur, the myosepta that separate them. Myomeres form of the gut, melanistic (brown or black) of some metalarvae and most juveniles are pigment patterns, osteological characters, and difficult to observe even with polarizing to a limited extent, morphometrics and meris- filters; reflected light at a low angle from one tics (especially dorsal fin ray counts for side and higher magnification sometimes metalarvae and juveniles). facilitates observation. There is often a noticeable amount of Typical counts used in taxonomic work intra- as well as inter-regional variability in include total, preanal, and postanal myo- many of the characters to be discussed. This meres. Partial counts are frequently used to variability necessitates confirmation of iden- reference location of various structures in tity based on as many diagnostic characters addition to the vent. The most generally as possible. accepted method of making partial counts was described by Siefert (1969) for distinguishing preanal and postanal myomeres: Myomeres "postanal myomeres include all [entire] myomeres posterior to an imaginary vertical line Myomeres, because they are obvious drawn through the body at the posterior end morphological features and relatively con- of the anus .. . Remaining myomeres, includ- sistent in number and position, are one of the ing those bisected by the line, are considered most useful characters available for identifica- preanal." The technique is equally applicable tion of larvae above (and sometimes at) the with other structures or points of reference species level, especially for protolarvae and such as origins of fins or fmfolds. The

9 opposite approach was used by Snyder et al. mesolarval phase, the soft-rayed portions of (1977), Snyder and Douglas (1978), Loos and the median fms (dorsal, anal and caudal) Fuiman (1977) and, according to the latter differentiate from this finfold. As the median authors, Fish (1932) -- only entire myomeres fins develop, the finfold diminishes and were included in counts anterior to points of recedes before and between the fins until it is reference. Siefert's method is recommended no longer apparent during or near the end of as standard procedure since resulting counts the metalarval phase. are expected to more nearly approximate the number of vertebrae to points of reference. The preanal finfold is a second median fold of tissue that extends forward from the In the United States and Canada, the vent. In most fishes the preanal finfold is range of total myomere (and vertebral) completely separated from the ventral portion to 52, is slightly larger counts for cyprinids, 28 of the median finfold by the vent. But in And nearly includes that for catostomids, 32 burbot (Lota Iota), and its marine relatives to 53. Ranges for preanal and postanal myo- (Gadidae, codfishes), the preanal finfold is mere counts also overlap with 19 to 35 and 9 initially continuous with the median fmfold respectively, for cyprinids and 25 to 42 to 22, and only later are the finfolds entirely separ- respectively, for and 5 (possibly 3) to 14, ated by the vent (vent initially opens through Despite the magnitude of over- catostomids. right side of finfold). The preanal finfold lap in these ranges, proportions of postanal may or may not be present upon hatching, preanal to total myomeres will to preanal and depending upon size and shape of the yolk distinguish most cyprinids from catostomids sac. In cypriniform fishes, it is typically (Snyder 1979). The preanal to postanal myo- absent or barely apparent upon hatching. As mere proportion is at least 2/5 (often greater yolk is consumed and the yolk sac decreases than 1/2) for cyprinids (exclusive of subfamily in size prior to hatching or during the proto- Cyprininae, the carps) and less (often less larval phase, a small preanal finfold appears than 1/3) for catostomids. Also, the propor- just anterior to the vent. As more yolk is tion of preanal to total myomeres is 5/7 or consumed and the larva grows, the preanal 2/3) for cyprinids and less (often less than finfold enlarges and extends anteriorly. greater (often greater than 3/4) for catos- Ultimately, its origin lies anterior to that of For cypriniform fishes in the Upper tomids. the dorsal portion of the median finfold. The Colorado River System the degree of overlap preanal finfold remains prominent throughout in total and preanal myomere counts is less the mesolarval phase, then slowly diminishes and larvae with fewer than 42 total or 32 and recedes in a posterior direction during preanal myomeres can be cyprinids only. the metalarval phase. It is typically the last finfold to be absorbed or lost. Fins and Finfolds The caudal fin is the first fm to differ- Fin ray meristics and fin positions are entiate from the median finfold in cyprini- among the most useful characters for later form and most other fishes with homocercal mesolarvae and metalarvae, especially among tails. The portion of the finfold involved first the cyprinids. These data can be determined thickens along the ventral side of the poster- from older juveniles and adults or gleaned ior end of the notochord and begins to differ- from published descriptions of adults. The entiate into the hypural elements of the cau- sequence and timing of fm development, fm dal skeleton. Immediately thereafter, the first lengths, and basal lengths of the dorsal and caudal fm rays appear (beginning of flexion anal fins are also useful. mesolarval phase) and the posterior portion of the notochord begins to bend or flex The median finfold, one of the most upward. Be careful not to confuse striations obvious structures in protolarvae and meso- or folds in the fmfold with developing fm larvae, is a thin, erect, medial fold of tissue rays. As the fm develops and the notochord that originates on the dorsal surface usually continues to flex upward, the hypurals and well behind head. It extends posteriorly to developing caudal fm rays, all ventral to the and around the end of the notochord, then notochord, move to a posterior or terminal anteriorly along the ventral surface to the position. The first principal rays are medial posterior margin of the vent. During the and subsequent principal rays form and pro-

10 gressively above below. Principal caudal fin might otherwise be considered as separate fin rays articulate with hypural bones of the rays. caudal structure and ultimately include all branched rays plus two adjacent unbranched Principal dorsal and anal fin ray counts rays, one above and one below the branched between and within certain genera often vary rays. Branching and segmentation of rays can sufficiently to be of use in identification at the be observed as or shortly after the full com- species level, especially anal fin rays of plement of principal rays becomes evident cyprinids and dorsal fin rays of catostomids. and notochord flexion is completed (begin- Positions of dorsal fin origin (anterior attach- ning of postflexion mesolarval phase). ment) and insertion (posterior attachment) relative to origin of pelvic fins or fin buds and The number of principal caudal fin rays the vent vary considerably among cyprinids is typically very stable within major groupings and are useful in identification of genera or of fish. Cyprinids generally have 19 principal species. These position characters are more rays (ten based on superior hypurals and nine consistent among catostomids (e.g., dorsal fm on inferior hypurals), and catostomids usually origin is always well in advance of the pelvic have 18 principal rays. fins), especially at subfamily level, and there- Dorsal and ventral rudimentary rays of fore, are of less value in identification. the caudal fin begin forming sequentially in The pelvic fins begin as buds before or an anterior direction immediately after all or upon transition to the metalarval phase. In nearly all principal caudal fin rays are cypriniform fishes, they originate in an abdo- formed. They are often the last group of fin minal position along each side of the preanal rays among all fins to form their full adult finfold. They may erupt shortly after dorsal complement. Accordingly, counts of rudi- and anal fin development begins or be delay- mentary caudal fin rays are usually ignored in ed until just before or shortly after all larval fish identification, but they may be of principal rays are present in the median fins. taxonomic value for juveniles and adults. Pelvic rays begin to form shortly after the buds appear and the adult complement of The dorsal and anal fins, which typically rays quickly ensues. Among cypriniform form either simultaneously (many cyprinids) fishes, pelvic ray counts are seldom used or dorsal first (most catostomids), usually diagnostically. However, position of the pel- begin development prior to attainment of the vic fins or fm buds, relative to other struc- full complement of principal caudal fm rays. tures, and their formation in the sequence of Tissue first aggregates in vicinity of the future developmental events can be useful in identi- fin, and basal structures or pterygiophores fication, especially among cyprinids. soon become evident. The latter structures permit limited use of dorsal and anal fin The pectoral fins typically begin as buds position and meristics about midway through immediately behind the head in the late the mesolarval phase. Anterior principal fm embryo. However, pectoral buds are not evi- rays develop first and subsequent rays are dent in some cypriniform fishes until shortly added in a posterior direction. The first after hatching. Though strongly striated and rudimentary fin rays (anterior to the principal rays) are frequently evident before all the occasionally with membranous folds and principal fin rays form. Rudimentary fm rays breaks, they typically remain rayless in are added in an anterior direction. cypriniforms until late in the mesolarval phase when most of the principal median fin The first or most anterior principal ray in rays are present. With the exception of rudi- both dorsal and anal fins remains unbranched mentary caudal fm rays, the rays of pectoral while all other principal fin rays branch fins are often the last to establish their full distally as or after ray segmentation becomes complement. For this reason and because evident. The last or most posterior principal the number of pectoral rays is usually rela- ray in each fin is considered to be divided at tively large and difficult to count without the base and therefore usually consists of two excision (especially the smaller ventral rays), elements that, except for their close proximity pectoral fin ray counts are generally of little and association with the same pterygiophore, value in larval fish identification.

11 Other Countable Structures components and dimensions and may be critical to species identification. Such measure- Other structures that may be treated ments may be allometric, changing in propor- meristically (and in some cases morphologi- tion as the fish grow; thus morphometric data cally) include branchiostegals, gill rakers, should be related to size, at least for proto- pharyngeal teeth, and scales. Branchiostegals larvae and mesolarvae. Some morphometric form early in larval development, but counts data, particularly body depths and widths, are usually constant within major taxon may be directly affected by the condition of groups. Within the order Cypriniformes, all individual specimens and volume and form of members of superfamily Cyprinoidea, which food items in their digestive tracts. The includes Cyprinidae and Catostomidae, have source of specimens and the preservative in three branchiostegals (McAllister 1968). Due which they are stored also may affect mor- to later development, small size or internal phometric data. Some measures in wild fish location, the other characters are seldom may differ from those of laboratory reared used to diagnosis fish larvae. Gill rakers specimens (e.g., fm lengths). Shrinkage and form gradually in postflexion mesolarvae or deformation are notably greater in alcohol metalarvae with numbers increasing through- than in formalin preservatives. out much of the early portion of the juvenile period. The adult complement of gill rakers Morphometric data in this guide are on the first gill arch is not achieved in many reported as percentages of standard length. Catostominae until they reach about 70 mm Use of standard length avoids the allometric standard length (Smith 1966). Pharyngeal influence of caudal fm growth included in teeth form relatively early but may not be percentages based on total length. As sufficiently well developed to be readily explained later (Methods), data can be easily removed and observed until late in the larval converted to percent total length for compar- period or early in the juvenile period. ison with other works. Prior to hypural plate Detailed study of gill rakers and pharyngeal formation and completion of notochord flex- teeth might reveal some useful diagnostic ion (protolarvae and flexion mesolarvae), qualities, including size, shape, and number. standard length is the length from snout to However, most specimens are more easily posterior end of the notochord (notochord identified using external characters. Scales length). Thereafter, it is the length from typically become apparent late in the larval anterior margin of the snout to most poster- period or early in the juvenile period. First ior margin of the hypural plates (usually the scales on cypriniforms typically appear mid- superior plate or hypurals). Use of noto- laterally on the posterior half of the body and chord length for protolarvae and early meso- from there spread anteriorly, dorsally, and larvae gives the appearance of greater allo- ventrally toward adult coverage. Scales of metric growth differences than may really large-scaled species are sometimes sufficiently exist, at least in comparison with subsequent obvious by late in the metalarval phase to measures based on posterior margin of the distinguish certain species or genera. hypural plates. This undesirable effect is a result of upward bending or flexing of the Morphology notochord and the switch from use of end of the notochord to posterior margin of the The shape or form of larvae and specific hypurals as the basis for length measurement. anatomical structures (e.g., gut, air bladder, These factors must be taken into account yolk sac, and mouth) change as fish grow and when reviewing morphometric data herein. provide some of the most obvious characters for identification, particularly at family and In contrast to procedures recommended subfamily levels. Within genera, morpholog- by Hubbs and Lagler (1958) for larger juven- ical differences among species are usually iles and adults, measurements of body length much more subtle, but may still be of diag- and various parts thereof for fish larvae are nostic value. Much shape or form-related generally taken along lines parallel to the information can be quantified via propor- horizontal axis of the fish. Exceptions are fin tional measurements or morphometrics. lengths, which in studies conducted for this manual were measured from origin of the fm Morphometric data emphasize the rela- base to most distal margin of the fin rays. tive position and relative size of various body Typical measures include total, standard,

12 head, snout, eye, and fm lengths, as well as mined while examining the specimen from snout-to-vent and snout-to-origin-of-fm (dor- above or below and, if necessary, holding the sal, anal and pelvic) lengths. fm away from the body. Snout-to-vent length is measured to the Body depths and widths are measured in posterior margin of the vent or anus. It is a planes perpendicular to the horizontal axis of primary diagnostic character for many spe- the fish. Many biologists report these as cies, especially at the family and sometimes maximum or minimum measures (e.g., great- subfamily level. In the Upper Colorado est head depth, greatest body depth, and least River System, most cyprinid larvae are readily caudal peduncle depth). However, for com- differentiated from catostomid larvae by parative purposes, it seems more logical to snout-to-vent lengths less than 72% SL. specify standard reference points for such Exceptions are most larvae of common carp measures as was done by Moser and Ahl- (Cyprinus carpio) and occasionally mesolarvae strom (1970), Fuiman (1979), and Snyder and of Colorado squawfish. The term "preanal Douglas (1978). Five specific locations, four length" is often applied to this measure but corresponding to specific length measure- might be misinterpreted as length to origin of ments, are used herein: (1) immediately the anal fm. For many fishes, including posterior to eyes, (2) origin of pectoral fm, cypriniforms, the latter measure is approx- (3) origin of dorsal fm, (4) immediately imately the same as snout-to-vent length since posterior to vent, and (5) at anterior margin the anal fin begins at or near the posterior of most posterior myomere (along the hori- margin of the vent. zontal myosepta). It is often desirable to Head length is typically measured to the approximate position of reference points in posterior margin of the operculum in juven- larvae prior to formation of the referenced iles and adults, but the operculum may be structure (e.g., origin of dorsal fm in absent or incomplete throughout much of the protolarvae and flexion mesolarvae based on larval period. Accordingly, many biologists position in later stages). Neither fms nor have redefmed head length for larvae to be fmfolds are included in depth measurements measured to the posterior end of the auditory herein. As mentioned earlier, care must be vesicle or the anterior or posterior margin of used in evaluation of depth and width mea- the cleithrum, one of the first bones to ossify sures affected by body condition and gut in fish larvae (Berry and Richards 1973). contents (e.g., measures at the origin of the Unfortunately, the auditory vesicle and dorsal fm). cleithrum are not always easy to observe, Other morphological characters such as especially in postflexion mesolarvae and position, size, and form of the mouth and gut, metalarvae. Also, resultant measures to the and related changes, can be among the more auditory vesicle are considerably anterior to useful characters for identification to the the eventual posterior margin of the oper- species level. Size of the mouth, as well as its culum. Snyder et al. (1977) and Snyder and position, its angle of inclination, and the form Douglas (1978) measured larval head length of specific mouth structures are diagnostic for to origin (anterior insertion) of the pectoral some cypriniforms, especially in metalarvae. fin. This measure has distinct advantages Timing of mouth migration from terminal to over the alternatives -- the base of the inferior position can be especially useful for pectoral fm is readily observed throughout catostomid metalarvae. Gut loop length, tim- the larval period (except in the few species ing of loop formation, and eventual degree that hatch prior to pectoral bud formation), and form of the gut loops, folds, or coils can it somewhat approximates the position of the be diagnostic for the larvae many fishes. cleithrum (part of its supporting structure), Such characters are especially useful in and it more nearly approximates the posterior distinguishing postflexion mesolarvae, meta- margin of the operculum than does the pos- larvae and early juveniles of certain catos- terior margin of the auditory vesicle. Accord- tomids. ingly, we recommend this definition of head length (Snyder 1983b) and have used it in all Pigmentation our descriptive work. For purposes of consis- tency, we apply it to juveniles as well as Basic patterns of chromatophore distribu- larvae. The measure is most precisely deter- tion, and changes in these patterns as fish

13 grow are often characteristic at the species For a specific species and developmental level. Used with caution, preferably in com- stage, pigmental variation is largely a function bination with other characters, and with an of number of chromatophores exhibiting pig- awareness of both intra- and inter-regional ment, either in general or in specific areas, variation, chromatophore distribution and and not a change in chromatophore pattern patterns for many fishes are among the most or distribution. Lack of pigment in chroma- useful characters available for identification. tophores of a particular an area, precludes However, in some instances, differences are that portion of the visible pattern. In addi- so subtle or variation so great that use of tion, pigment in chromatophores can be var- pigmentation is impractical and may be iously displayed from tight, contracted spots, misleading. resulting in a relatively light appearance, to widely expanded, reticular networks, resulting In cypriniform and most other fishes, in a dark or more strongly pigmented appear- chromatophores other than melanophores ance in the affected area. Differences in have not been sufficiently studied for environmental conditions and food can signi- identification purposes. Such chromato- ficantly affect the presence and displayed phores are typically neither as numerous nor form of pigmentation. Accordingly, research- as obvious as melanophores and their pig- ers must be aware that pigmentation of cul- ments are difficult to preserve. In contrast, tured specimens can appear quite different melanin, the amino acid breakdown product from that of field-collected material. responsible for the dark, typically black, appearance of melanophores (Lagler et al. Pigmentation often changes considerably 1977), remains relatively stable in preserved as larvae and early juveniles grow. Most of specimens. However, melanin is subject to the change is due to increased numbers and fading and bleaching if specimens are stored distribution of chromatophores. Observable or studied extensively in bright light for long pigmentation might also be lost from certain periods of time, stored in highly alkaline pre- areas through loss of pigment in chromato- servatives, or subjected to changing concen- phores, loss of chromatophores themselves, trations of preservative fluids. To minimize or, in the case of subsurface or internal the latter effects, as well as shrinkage and chromatophores, by growth and increased deformation, dilute formalin solutions (3-5%, opacity of overlying tissues. Peritoneal unbuffered or buffered to near neutral) are melanophore pigmentation is an obvious strongly recommended over alcohol solutions character for later stages of some larvae But as storage media. Most of the following dis- in late metalarvae and especially juveniles, cussion refers to chromatophores in general, dark peritoneal pigmentation can be obscured but in this manual and others for freshwater by overlying tissues with silvery iridophores species in North America, pigmentation typi- (this silvery pigment often dissip,ates over cally refers to that of melanophores. time in preservative). If internal melanophore pigmentation is obscured by overlying According to Orton (1953), pigment cells tissues, it can be observed by selective originate in the neural crest region (dorsal dissection or careful clearing of specimens. portion of body and tail) and migrate in amoeboid fashion in waves to their eventual position. The first wave of chromatophores occurs late in the embryonic period or early Osteology in the larval period and establishes a rela- When externally visible characters fail to tively fixed basic or primary pattern of segregate species conclusively, osteological chromatophore distribution. In a few species characters may come to the rescue. While (mostly marine), such cells acquire pigment whole-specimen clearing and cartilage- and prior to chromatophore migration and the bone-staining techniques are relatively simple actual migration can be observed and docu- (see Methods), they require much time (a mented. But in cypriniform and most other few days, mostly waiting) and a fair amount freshwater fishes, pigment is not present in of attention (monitoring progress and chang- chromatophores until after the cells reach ing fluids). Soft (longwave) X-ray techniques their ultimate destination. (Tucker and Laroche 1984) may be faster and

14 easier, especially when examining many speci- ciated bones. Once the axial skeleton is mens, but they require appropriate X-ray sufficiently established, median- and pelvic- equipment and a darkroom. fin supports form, and fins develop. Pre- sence, number, position, and shape of certain Dunn (1983, 1984) reviewed use of skele- bones in many parts of the skeleton can have tal structures and the utility of developmental diagnostic value, even for closely related osteology in taxonomic studies. Among the species. Use of osteological characters for first bones to ossify are those associated with identification of fish larvae has received little feeding, respiration, and orientation (e.g., attention, but its potential value is great, jaws, bones of the branchial region, clei- particularly for confirmation of questionable thrum, and otoliths). The axial skeleton identities and for species in which external follows with formation of vertebrae and asso- characters are diagnostically inadequate.

SPECIMENS EXAMINED

Cultured specimens were analyzed for son River between Whitewater and Redlands each species. Developmental series for all Dam. Analyzed mountain sucker specimens but Utah sucker were reared by the Larval were collected in 1981 from Willow Creek Fish Laboratory from artificially-fertilized (and Ways Gulch) in Colorado, and in 1982 eggs during 1978 through 1981. Parental through 1986 from the Provo and Spanish stock for culture of flannelmouth sucker was Fork Rivers in Utah. Mountain suckers collected from the Yampa River near Juniper collected in 1973 through 1982 from the Truc- Springs; bluehead sucker from the White kee River and Pyramid Lake, Nevada, and in River near Rio Blanco Lake; mountain suc- 1966 and 1967 from Rocky Creek, Madison ker from Willow Creek, headwater tributary River, and Flathead Creek (all tributaries of to the Elk River (tributary to the Yampa the Missouri River) in southcentral Montana River) northwest of Steamboat Springs; were cursorily examined. Partial series of razorback sucker from a gravel pit off the razorback sucker larvae were analyzed from Colorado River near Clifton; and white collections in Lake Mohave and a March 20, sucker from a private pond southwest of Fort 1984, collection from the Salt River at Horse- Collins. Razorback sucker larvae and juven- shoe Bend in Arizona (the latter were reared iles were reared also by Dexter National Fish at Dexter National Fish Hatchery and stocked Hatchery in 1982 from Lake Mohave stock. a week prior to capture). Utah sucker specimens were reared by the Most of the collected and reared speci- Utah Cooperative Fish and Wildlife Research mens were killed and fixed in 10% formalin, Unit in 1987 from Bear Lake stock. then stored in 3% buffered formalin. Some Wild or field-collected specimens of mountain sucker specimens from Montana certain identity were analyzed also for all were preserved in ethyl or isopropyl alcohol species except Utah sucker. Flannelmouth, solutions. Due to excessive dehydration and bluehead, and white sucker larvae and juven- shrinkage, none of the latter specimens were iles were collected during 1976 through 1979 analyzed for measures or size relative to from the Yampa River from west of Milner developmental state. to the Lily Park area below Cross Mountain Canyon. Analyzed flannelmouth and blue- All specimens used for morphometric head sucker larvae were collected also from and skeletal analysis, and most of other speci- the White River between Rio Blanco Lake mens on which this study is based are main- and Spring Creek. Additional flannelmouth tained in collections of the Larval Fish Labor- and bluehead sucker specimens were cursorily atory and are available for examination by examined from 1977 through 1979 collections other researchers. Individual specimen data in the Colorado River between Palisade and (counts and measures) are stored in IBM PC- the Colorado-Utah border and in the Gunni- compatible computer files (Lotus 123).

15 METHODS

Specimen Data and Observations Drawings, including dorsal, lateral, and ventral views, were prepared for the begin- Specimens were analyzed for counts, ning and middle of each larval phase (flexion measures, developmental state, structural and postflorion mesolarvae treated as one differences, and pigment distribution. Fig. 4 phase) and the juvenile period (young-of-the- illustrates the various measurements, fm ray year portion) for all species except white counts, and myomere counts that were made sucker to document typical body form and on at least two specimens, if available, in pigmentation. Enlarged photographs of each 1-mm TL (total length) interval typical specimens were traced to assure throughout the larval period of each species. accurate body proportions. Various struc- Thereafter, to a length of about 50 mm TL, tures were checked and additional detail was one or more specimens were similarly pro- added to drawings while specimens were cessed for each 5-mm interval, if available. examined under a microscope. Final draw- Specimens were studied under low-power ings were idealized (e.g., closed or frayed fins stereo-zoom microscopes with measuring eye- opened and smoothed and curved bodies piece reticles and various combinations of straightened). If necessary, melanophore dis- reflected, transmitted, and polarized light. tribution was modified using additional refer- Magnification was adjusted before each series ence specimens to represent a more typical of measurements to calibrate the scale in the pattern. In addition, pigmentation variation eyepiece against a stage micrometer for direct was studied by sketching observed patterns measurement. Measurements were made to and loosely noting their frequency. the nearest 0.1 mm and occasionally to half Selected postflodon mesolarvae, meta- that unit. Remeasurement of selected speci- larvae, and juveniles were cleared and stained mens by a second observer indicated that for examination of potential osteological char- most measurements are repeatable to within acters and vertebra counts as well as to verify 0.1 mm. Most measurements are reported as fin meristics. Shape and size of the fronto- a percentage of standard length (% SL) but parietal fontanelle, interneurals, and anterior- are readily converted to percent total length dorsal maxillary projections; position of man- by dividing the length of interest (as % SL) dibles relative to maxillae; and, to a less by total length (AS to PC, as % SL), and consistent extent, angle at which the base of multiplying by 100. Some meristic data were postcleithra extend from the cleithra (Fig. 6). obtained from specimens cleared and stained Mesolarvae were stained with alcian blue for for skeletal study and from available adults. cartilage and metalarvae and juveniles with alizarin red for bone using the procedures Size at apparent onset of selected devel- given on the following pages. opmental events was documented for fully analyzed and cursorily examined specimens. Keys were produced with the aid of the Selected events were hatching, attainment of DELTA (DEscriptive Language for TAxon- eye pigment, formation of pectoral and pelvic omy) system of computer programs (Dallwitz fin buds, loss of yolk and preanal finfold, 1974, 1980; Dallwitz and Paine 1986). Char- formation of first and last principal fin rays in acters were encoded using the DELTA for- each of the median fins, formation of first mat then transformed for use by the program and last fin rays in the paired fms, formation KEY. Due to limitations of the current MS- of first and last rudimentary rays of the DOS version of KEY and the numerous over- caudal fin, and initial and complete formation lapping characters of the species considered, of lateral scales on the body. For each speci- output was generated in segments, each res- men developmental phase (e.g., Protolarva) tricted to a select set of characters and and extent of gut folding were also deter- species. These were then edited to remove mined. The latter was classified as one of repeated branches and phrases and assemb- five gut phases (Fig. 5). Changes in other led into a complete key for each develop- structures were only casually noted. mental phase.

16 width anddepthmeasuresbutfins andfinfoldsarenot."B"inBPEBPVmeansimmediatelybehind. AMPM to specificpoints ofreferenceareshadedabove. (FromSnyder1981.) rudimentary raysarenotdistinguished inpairedfins.Mostanterior,mostposteriorandlastmyomeres incounts in lowercaseRomannumerals,while principalmedianfinrays(darkenedabove)aregiveninarabic numerals); is approximatedtothatoflaterlarvae. PHPismeasuredtoendofnotochorduntiladultcomplement ofprincipal is anteriormarginofmostposterior myomere.LocationofwidthanddepthmeasuresatODpriorto Dformation origin tomostdistalmargin.When reportedtogether,rudimentarymedianfinrays(outlinedabove) aregiven caudal finraysareobserved.Fin lengths Fig. 4. LENGTHS FROM SNOUT ---IWIDTHS1.---- Measures andcountsforlarval earlyjuvenilefishes.Yolk-sacandpterygiophoresareincluded in ,.. ,,, . . , ..., 0 42 X ,,,_, 0 0 Li L C M M C

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PHASE 1

PHASE 2

PHASE 3

PHASE 4

PHASE 5

ADULT FORM

Fig. 5. Phases of gut coil development in catostomid fish larvae and early juveniles with comparison to adult form in Catostomus commersoni (latter modified from Stewart 1926). Phase 1 -- essentially straight gut. Phase 0 2 -- initial loop formation (usually on left side), begins with 90 bend. Phase 3 -- full loop, begins with straight loop extending to near anterior end of visceral cavity. Phase 4 -- partial fold and crossover, begins with crossing of first limb over ventral midline. Phase 5 -- full fold and crossover, begins with both limbs of loop extending fully to opposite (usually right) side, four segments of gut cross nearly perpendicular to the body axis. Later in Phase 5 and in adult form, outer portions of gut folds or coils extend well up both sides of visceral cavity.

18 Interneurals vials. Times for other sizes and numbers of specimens can be approximated accordingly. Vertebrates as large as 500 mm have been cleared and stained by these procedures but ,0 time requirements are considerably greater; 7 clearing alone can take several weeks. Potthoff (1984) provides a diagram of approx- 4—Postcleithrum imate times for specimens 10 to 500 mm standard length. Specimens larger than 30 mm with scales or thick skin may need to be Anterior-Dorsal Projection scaled or skinned, or selectively and carefully punctured over the body with a sharp needle, prior to clearing and staining. Some larger specimens may need to be eviscerated. Fatty 4-Frontoparietal Fontanelle or oily specimens may need "degreasing" in xylene before staining or clearing and specimens with large amounts of guanine or similar white or silvery substances may needed Maxilla soaking in 2% or stronger potassium hydroxide solution after clearing by the enzyme method (Taylor and Van Dyke 1985). Specimens should never occupy more than 25% of solution volume during fixation; lesser percentages (e.g., 1510%) are recommended. During clearing and staining, results will be better and time requirements may be Fig. 6. Location of selected skeletal features ol less if specimens occupy much less than 10% metalarval and early-juvenile catostomids. Top- of solution volumes (e.g., down to 2% of lateral view. Middle-dorsal view. Bottom-ventral solution volume during neutralization and view. clearing). For specimens 30 mm total length or less, most or all steps can be carried out conveniently in 20 ml or similar-size vials. During each step, periodically turn or move Clearing and Staining Procedures specimens to minimize solution stratification for Skeletal Study of Small Fish and aid penetration of solutions into tissues of specimens being processed. These instructions are modified from For the most reliable results begin with Snyder and Muth (1988) and based on proce- freshly fixed and preserved specimens. Older dures detailed by Fish (1932, Method III), museum specimens may or may not clear and Taylor (1967), Potthoff (1984), and Taylor stain properly depending on original fixative, and Van Dyke See Taylor (1967) and (1985). preservative, and subsequent care. However, Taylor and Van Dyke (1985) for detailed properly fixed and preserved specimens explanations and discussions of the various should clear and stain nearly as well as fresh steps, factors affecting them, and alternatives. material, even after a few decades. The procedures that follow are for With specific regard to fish embryos and differential staining of cartilage and bone larvae, Taylor and Van Dyke (1985) made the beginning with living specimens. To begin following observations. "The presence of with previously preserved specimens, stain cartilage in embryos and larval fishes is only for cartilage, only for bone, or clear readily determined by this method [differ- (make transparent) without staining, skip the ential staining with enzyme clearing]. But, irrelevant steps. determining the presence and time and/or Minimum and maximum times given in degree of osteogenesis is more difficult the procedures are approximate for single because newly deposited bone mineral is specimens measuring 10 and 25 mm total much more labile than mineral that has been length, respectively, and processed in 20 ml deposited for some time. The presence of

19 bone mineral is usually indicated by staining other trypsin preparations with activ- with alizarin Red S. This color may be faint, ities as low as 80 units/mg have also pink, or bright red in larval fishes with ages been used successfully) CL from unhatched embryos, through those with complete absorption of the yolk sac or even Stock Solutions: (applicable procedures as older. To state in the absence of the red above.) color that osteogenesis or bone development 10% buffered formalin solution is not present at any of these developmental In distilled water; buffer to pH 7.0 stages may be incorrect without microscopic with 4.0 g sodium phosphate mono- examination of tissue structure because bone basic and 6.5 g sodium phosphate may be in an early stage of development or dibasic per liter of formalin solution the mineral may have been removed during (recommended by Taylor and Van fixation, clearing or staining steps." They Dyke 1985), or to pH 6.8 with 4 g further observed that fish larvae with obvious each of monobasic and dibasic sod- bone, often lose bone stain while in enzyme ium phosphate per liter of formalin clearing solution, but that much of it remains solution. The latter is about twice in specimens cleared in potassium hydroxide the 1.8 g each of monobasic and solutions. Accordingly, they recommend that dibasic per liter recommended by fish larvae be fixed in neutral-buffered (pH Markle (1984) for 5% formalin solu- 6.5-7.2) formalin and that some be differen- tions. Formalin solutions can be tially stained for bone and cartilage, while buffered with excess marble or lime- others are stained for bone only and cleared stone chips or limestone powder to with potassium hydroxide (instead of near neutral, but phosphate buffering enzymes) soon after fixation. is more precise and reliable; borax Safety: Many of the chemicals and solutions (sodium borate) buffered formalin is used in clearing and staining can be hazar- not recommended (Taylor and Van dous and should be handled and disposed of Dyke). FP accordingly. 3-5% buffered formalin solution In distilled water; buffer with 1.8 g Chemicals: (applicable procedures: FP = fix- sodium phosphate monobasic and 1.8 ation and preservation; BL = bleaching; g sodium phosphate dibasic per liter CL = clearing, protein digestion; CS = of formalin solution (Markle 1984). cartilage staining; BS = bone staining.) Alternatively, fixed specimens can be stored in alcohol (e.g, 75% ethanol Alcian blue (powder) CS via a graded series of concentra- Alizarin red S (powder) BS tions), but expect greater shrinkage, Distilled water ALL deformation, and, if examined peri- Ethanol (absolute ethanol preferred, odically, fading of melanophore pig- denatured or 95% will suffice) CS mentation than if stored in dilute If used as preservative FP, CL formalin solutions. FP Formalin (saturated formaldehyde sol.) FP Glacial acetic acid CS 50% ethanol solution Glycerin (glycerol) In distilled water. CS If used as preservative CL If used in graded series for specimen Hydrogen peroxide, 3% solution BL preservation (storage). FP, CL Potassium hydroxide (KOH) BL, CL, BS 75% (or 70%) ethanol solution Sodium borate (powder) CS, CL In distilled water if used for speci- Sodium phosphate monobasic FP men preservation. FP, CL Sodium phosphate dibasic (anhydrous) FP Thymol (crystals) If glycerin is used CL Alcian blue stain solution Trypsin powder (pancreatic protease, 20 mg alcian blue per 100 ml of 30% pancreatin; sufficiently purified to be glacial acetic acid in ethanol (solution free of collagenase and elastase; will keep at room temperature for 3-4 trypsin from pig pancreas with an weeks). CS activity of 300 units/mg produces a Saturated sodium borate solution clear, highly effective solution, but Excess sodium borate powder in

20 distilled water; mix well and allow series of concentrations, e.g., 50% eth- excess sodium borate to settle; use anol for 6-24 hours then 75% ethanol). clear supernatant solution. CS, CL Do not soak in water between fixative and preservative solutions. 1% Potassium hydroxide (KOH) solution In distilled water. BL,CL,BS Cartilage Staining Procedure: 2% Potassium hydroxide solution 3. Dehydrate formalin-fixed and preserved In distilled water. specimens in 50% ethanol solution for 6- If KOH clearing used used. CL 24 hours, then in 100% or absolute ethanol for 12-24 hours. Replace the abso- Bleaching solution lute ethanol and leave at least another 15% of 3% hydrogen peroxide solu- 12-24 hours. A more gradual series of tion in 1% KOH solution. BL alcohol concentrations can be used, e.g., Trypsin solution 50%, 75%, and 100% but is usually un- About 0.1-0.2 g (depending on necessary. If specimens were preserved strength or activity level of trypsin) in alcohol, skip the 50% ethanol step. per 100 ml of 30% saturated sodium For embryos and larvae, dehydration is borate solution in distilled water; mix essential to assure minimal loss of bone well but do not allow to froth while in the acid stain for cartilage. (Taylor and Van Dyke 1985). Make a fresh solution for each use; it does 4. Stain specimens in alcian blue stain solu- not keep well. tion for 6-24 hours, no longer than nec- If enzyme clearing used. CL essary to adequately stain all cartilage. 5. Rinse specimens in saturated sodium Alizarin red stain solution Dissolve enough alizarin red powder borate solution then soak in fresh saturated sodium borate solution for 6-24 in 1% KOH to turn the solution hours to neutralize (change body fluid deep purple (about 0.1 g per 100 pH from acid to alkaline). ml). Or mix about 1 ml of a saturated alizarin red solution per 100 ml Bleaching: (Optional) of 1% KOH (saturated alizarin red solution is prepared by dissolving 6. If specimens are heavily pigmented (such excess alizarin red powder in small that pigments would obscure desired amount of distilled water, about 1.5- structures), bleach specimens by placing 2.0 g per 20 ml). Alizarin red stain them in bleaching solution and exposing solution will keep at least one them to strong light until chromatophore week. BS pigment is notably faded, about 20 min- utes to a few hours. 40% glycerin solution In 1% KOH (preferred) or distilled Initial Clearing: water. If glycerin is used. CL 7. Enzyme method. If specimens were not processed for cartilage staining, soak 70% glycerin solution them in saturated sodium borate solution In 1% KOH (preferred) or distilled for 2-12 hours to remove remaining for- water. malin or alcohol and adjust body fluids If glycerin is used. CL to well above pH 7. Soak specimens in trypsin solution until 75-90% of the Fixation and Preservation: muscle tissue is cleared, typically 1-5 days 1. Kill and fix specimens in 10% buffered at 20-30°C, possibly longer depending on formalin for 24-48 hours. specimen volume relative to solution volume and activity or strength of trypsin. 2. If specimens are to be stored more than Use a volume of trypsin solution at least a couple days before clearing and stain- 10 to 40 times the volume of specimens. ing, preserve them in 3-5% buffered for- Completely change trypsin solution every malin or alcohol (preferably via a graded 2-3 days. This method is preferred for

21 all fish except embryos and larvae in Final Clearing and Storage: which some critical bone mineral may be lost. For both freshly fixed and long pre- 9. Return specimens to clearing agent (tryp- served material, the enzyme method gen- sin solution or 1 or 2% KOH solution) erally provides more consistent results until remainder of muscle is adequately with firmer whole specimens than the transparent (some fmal clearing will take KOH method. place in glycerin series if used for storage). Change solution after an hour or or two to remove excess stain and continue clearing if necessary. If clearing in KOH KOH method. Soak specimens in 2% solution, monitor specimens closely (this KOH solution until muscle tissue begins procedure is usually faster and less for- to clear, typically 1 to 12 hours (use 1% giving than the enzyme method). KOH for very small and delicate specimens). Monitor specimens closely -- this 10. Specimens may be stored in alcohol (e.g., method of clearing is simpler, less expen- 75% ethanol), in which they are easier to sive, and tends to be faster than the handle, but "to attain uniformity in clear- enzyme method, but it is also more likely ing and avoid storage problems" (Taylor to result in fragile specimens with skin 1967), most researchers store cleared and that literally splits at the seams if the stained specimens in pure or 100% gly- specimens are inadequately fixed or if di- cerin. Glycerin also will reduce or gestion of tissues is allowed to go too far. eliminate cloudiness due to water in the Results are usually better and more con- remaining soft tissues. In either case, sistent if specimens are freshly fixed than work specimens through at least a mini- if they were preserved and stored for a mal graded series to the final concentra- long time (Taylor and Van Dyke 1985). tion, 4-24 hours in each solution (e.g., 50% and 75% ethanol or 40%, 70% and Bone Staining Procedure: 100% glycerin). If specimens are not as transparent as desired at this point, try 8. Stain specimens in alizarin red stain solu- adding a 20% glycerin in 1% KOH step tion until bones are adequately stained, a to the beginning of the graded glycerin few hours to one day; monitor specimens series. Add a few thymol crystals to closely. Rinse specimens briefly in dis- containers with 100% glycerin to prevent tilled water. fungus growth.

22 RESULTS AND CONCLUSIONS

Results are divided into three interrelated predominately rock or gravel substrates. sections -- Comparative Summary, Keys, and Their recently hatched larvae are photo- Species Accounts. Although 445 specimens phobic and usually hide or remain in the were analyzed in detail for morphometrics substrate for at least a few days before and meristics and hundreds more were docu- emerging and drifting with the current. mented for size, developmental state, skeletal Although considered broad-cast spawners, characters, and pigmentation patterns, there razorback sucker produce discrete, identi- are undoubtedly rare specimens with charac- fiable redds in reservoirs (Bozek et al. 1984). ter extremes beyond those we observed. For This may suggest tendency towards a brood- example, Kevin Bestgen, an associate studying hiding guild. larvae in the Lower Colorado River Basin, measured reared razorback sucker flexion Comparative Summary and postflexion mesolarvae as small as 10 and 11 mm SL, respectively. Those measures are The diagnostic criteria that follow are a millimeter less than the smallest specimens provided to help confirm identities determin- we measured and are included in the results ed through the keys or, for biologists familiar that follow. Because of the similarity among with the larvae of concern, to serve as a par- larvae of Upper Colorado River Basin suc- tial alternative to the keys. Since extremes in kers, the specific identity of some larvae will character states beyond those reported here remain inconclusive or questionable after are likely to occur, identifications should be application of the keys and diagnostic criteria based on as many criteria as possible. provided herein. The identity of such specimens must be considered tentative and Size relative to state of development: should be designated as such by use of a Flannelmouth sucker eggs are the largest of question mark ("?") after the more probable Upper Colorado River System suckers (3.8- taxon name (preferably with a footnote on 3.9 mm diameter versus 3.3-3.5 for blue-head other possibilities), or leaving the identity at sucker and 2.3-3.3 for the others) and larvae the family level (e.g., "unidentified Catosto- hatching from them are usually much larger midae"). Some inconclusive specimens may as well. This relative size difference is be hybrids. characteristic of flannelmouth sucker throughout its early development (Table 1). In con- Hybridization among Colorado River trast, razorback, mountain, and some white System catostomids is well documented (e.g., sucker eggs are notably smaller (2.3-2.8 mm Holden and Stalnaker 1975, Hubbs et al. diameter) than other species and their 1943, Hubbs and Hubbs 1947, Hubbs and recently hatched protolarvae and recently Miller 1953, McAda 1977, McAda and transformed mesolarvae tend to be corres- Wydoski 1980, Prewitt 1977, and Smith 1966). pondingly small. These species also complete Intermediacy of characters for white X blue- yolk absorption at a much smaller size, head sucker hybrids as small as 25 mm SL usually by 12 mm SL; flannelmouth larvae and flannelmouth X bluehead sucker hybrids finish their yolk at 15 mm SL. as small as 34 mm SL were documented by Size relative to state of development for Hubbs et al. (1943) and Hubbs and Hubbs all species but flannelmouth sucker is nearly (1947) respectively. Using diagnostic charac- the same by the beginning of the metalarval ters and descriptive data that follow, hybrid phase. Fin development tends to proceed metalarvae and early juveniles might be at fastest (at smaller sizes) for white sucker and least tentatively identified as such; hybrid slowest (at larger sizes) for flannelmouth protolarvae and mesolarvae will likely be sucker. White and Utah suckers acquire the identified as the parental species they most adult complement of all fin rays, lose their closely resemble or remain questionable. preanal fmfold, and become juveniles at the In the species account sections on smallest sizes (19-20 mm SL) while transfor- reproduction, all six suckers are classified mation to the juvenile period for some razor- according to Balon's (1975a, 1981) reproduc- back sucker occurs at sizes nearly as large as tive guilds as non-guarding, open-substrate, for flannelmouth sucker (22-23 and 23-24 mm lithophils. Lithophils prefer to spawn over SL, respectively).

23 Table 1. Comparison of size (mm standard length) at onset or transition of developmental intervals, gut phases, and other developmental events for larvae and early juveniles of Upper Colorado River Basin catostomids. Rare extremes in parentheses. • = "or before hatching."

Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen Character ardens commersoni discobolus latipinnis platyrhynchus texanus

Egg diameter. 2.9-3.2 2.6-3.3 3.3-3.5 3.8-3.9 2.3-2.7 2.5-2.8 Phase/period transitions Embryo to larva: (7)8-11 (7)8-10 (8)9-10(11) (8-)10-11 (7)8 7-9 Proto- to mesolarva: 12-13 10-12 10-12 13 11 (10)11(12) Flexion to postflexion mesolarva: 13-14 (12)13-15 (11)12-13 15 13-14 (11)12-13 Meso- to metalarva: 15-17 15-16(17) (16)17 19-20(21) 16-17 15-17 Larva to juvenile: 19-20 (17-)19-20 21-22(23) 23-24(25) 21-22 (21)22-23(24) Gut phase transitions 1 to 2 (90° bend): 14-17 14-15(16) 14(15) (17)18(-20) 14-17 (14)15(-17) 2 to 3 (full loop): 18-19 (16)17-18 15(16) (19-)21-25(-27) 16-17 17 3 to 4 (partial crossover): 20-22 19-20(21) (16)17 (22)23-32(-37) 18-20 18-25(26) 4 to 5 (full crossover): 27-28 (20)21-25 (16)17-19(-21) (29-)35-42 21-23 (22-)26-28(-31) Onset of selected events Eyes Pigmented: 9-10 ' (7)8 * 9-10 • (9)10 * 8 (7)8(9) • Yolk Assimilated: 12-13 10-12(-14) (10-)12-13 15 (10)11 (9)10-11 Finfold Absorbed: 19 (17-)19-20 21-22(23) 23-24(25) 21-22 (21)22-23(24) Pectoral Fin Buds: (7) • (7)8 • (8) * (9) • (7) • 7 * Pelvic Fin Buds: 13-15 13-15 14 (15)16(17) 13 14 Fin rays first observed Dorsal, principal: 13-15 12-13 (11-)13 15 13 14 Anal, principal: 14-15 14-16 14-15 17 16-17 15 Caudal, principal: 12-13 10-12 10-12 13 11 11 Caudal, rudimentary: 14-15 13-15 14 (16)17 14 14 Pectoral: 14-15 14-16 14-15 17 13-15 15 Pelvic: 14-17 15-16 16 17-18 16 15-17 Full fin ray counts first observed Dorsal, principal: 14-16 14-16 (14)15 17-18 14-17 15(-17) Anal, principal: 15-17 15-16(17) (16)17 19-20(21) 16-17 15-17 Caudal, principal: 13-14 (12)13-15 (11)12-13 15 13-14 12-13 Caudal, rudimentary: 19-20 (17)18 19-20 23 20-21 19-20(-24) Pectoral: 15-18 16(-20) 16-18(19) 19-22 18-20 16-18 Pelvic: 18-19 16-18 19-20 23 18-20 16-17 Scales, lateral series First observed: 21-23 22(23) 28-34 (36)37-39 23-24 24-28 Full series first observed: 24-28 29-31 30-39 39-42 32-36 33-36(37)

Gut folding or coiling proceeds at a appears as early as 24 mm SL for Utah suc- faster rate for most bluehead sucker than for ker and 29 mm SL for white sucker, both of other species and at a much slower rate for which have large scales. But it appears no nearly all flannelmouth sucker. Although gut earlier than 39 mm SL for flannelmouth that folding begins only a little later in razorback has very fine scales. larvae than in bluehead larvae, it slows during Meristics and morphometrics: Some the metalarval phase. As a result, the upper character differences determined by compar- end of the size range for razorback sucker at ison of species account summaries of meris- transition to gut phase 4 overlaps the lower tics and morphometrics are not included in end of the range for flannelmouth sucker. Tables 2 and 3 because corresponding data The size at first appearance of the full for an adjacent phase indicate that the differ- series of lateral scales roughly correlates with ences might not hold up if additional speci- scale size. The full lateral series of scales mens in the size range of concern are anal-

24 yzed. When comparing morphometric char- As would be expected, vertebra counts acters, be aware that some characters, espec- (based on specimens cleared and stained for ially depths and widths at OD and 0P2, are cartilage or bone) nearly match or fall within affected by the amount of yolk in early larvae the range of total myomere counts (all larval and by health or condition in later larvae and phases combined). The one notable excep- juveniles. tion, an upper extreme of 50 vertebrae for the mountain sucker is based on one verified The more useful meristics are counts of observation over 48. The greater range in lateral line (or series) scales for juveniles in values for myomere counts, especially at the which scales are sufficiently formed; principal lower end, is due to the far greater number dorsal fin rays (and corresponding pterygio- of specimens examined for myomere counts phores) and vertebra for late postflexion (vertebra counts are based on only a few to mesolarvae, metalarvae, and juveniles; and several observations per species) and the myomeres, both total and to the posterior difficulty in observing first and last myomeres margin of the vent, for all larval phases in some specimens, especially metalarvae for (Table 2). White and Utah suckers usually which polarizing filters are no longer useful. have fewer than 75 lateral rows of scales Probably for the latter reason, both total and while bluehead and flannelmouth suckers to-the-vent myomere counts for metalarvae usually have over 85, and mountain and tend to range one or two myomeres less than razorback suckers typically have counts for protolarvae and mesolarvae. A slightly between 75 and 85. Typical counts of princi- more anterior vent position in metalarvae pal dorsal fin rays are highest for razorback (and juveniles) than in earlier larvae might sucker with 14-15, and lowest for mountain also account for some of the difference in sucker with 10; the other species have typical myomere counts to the posterior margin of counts within the 11-13 range. However, the vent. Combined total vertebrae and myo- when considering observed extremes in these mere counts are greatest for bluehead and counts, three species have ranges that include flannelmouth sucker (typically 47 or greater) the count of 14 and four species include the and least for Utah, white, and mountain suc- count of 10. ker (typically 47 or less); razorback sucker

Table 2. Comparison of the more diagnostic differences in meristics for larvae and early juveniles of Upper Colorado River Basin catostomids. Character range is followed by the mean or more typical range. See Fig. 4 for methods of counting myomeres and fin rays. PV = posterior margin of the vent. Vertebra counts include four for the Weberian complex; dorsal fin ray counts are of principal rays; scale counts are of the lateral line or series. Data previously published by other authors is given in parentheses.

Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen Character ardens commersoni discobolus ladpinnis platyrhynchus tetanus

Myomeres to PV Proto- and mesolarvae: 35-38, 36-37 34-40, 37-38 37-40, 39 37-40, 39 34-37, 36 37-41, 38-39 Metalarvae: 34-37, 36 34-37, 35 35-38, 37 36-38, 37 32-36, 35 36-39, 37 All larvae: 34-38, 36-37 34-40, 35-38 35-40, 37-39 36-40, 37-39 32-37, 35-36 36-41, 37-39

Myomeres, total Proto- and mesolarvae: 45-48, 46 43-49, 46-47 47-49, 48 47-49, 48 43-47, 45-46 46-49, 47-48 Metalarrae: 43-47, 45 44-47, 45 47-48, 47 46-48, 47 43-45, 45 44-48, 46 All larvae: 43-48, 45-46 43-49, 45-47 47-49, 47-48 46-49, 47-48 43-47, 45-46 44-49, 46-48

Vertebrae: 47-48 45-48, 46 47-49 47-50 46-50, 46-48 45-47, 46 (44-48) (45-50, 47-49) (42-48,44-47)

Dorsal fin rays: 10-14, 11-13 10-13, 11-12 9-12, 11 11-14, 12-13 9-11, 10 12-16, 14-15 (11-13) (9-15, 10-13) (9-12, 10-11) (10-15, 12-13) (8-13, 10) (12-16,14-15)

Lateral line scales: 57-68, 62-68 56-72, 59-68 76-86 (54-79, 60-70) (53-85, 56-76) (78-122,86-115) (89-120,98-105) (60-108,75-97) (68-95,76-87)

25 Table 3. Comparison of the more diagnostic differences in morphometrics for larvae and juveniles (-40 mm SL) of Upper Colorado River Basin catostoznids. Except as otherwise noted for most eye diameters, all data is given as a percentage of standard length. The full range for each character is followed by the mean or more typical range. See Fig. 4 for abbreviations and methods of measurement. HL = head length measured to origin of the pectoral fm (AS to OP1).

Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen Character ardens commersoni discobolus lanpinnis platyrhynchus tetanus

Protolarvae Eye diameter:A 5-7, 6 5-7, 6 5-6, 5 5-4, 5 6-8, 7 5-6, 6 AS to PE length: 7-9, 8 8-9, 8 6-7, 7 6-9, 7 8-10, 9 7-8, 8 AS to OP1 length: 12-17, 15 13-19, 16 13-15, 14 12-16, 14 16-18, 17 14-17, 16 Yolk length: 49-64, 57 26-63, 51 61-67, 63 54-67, 61 0-67, 47 0-68, 44 b Pectoral fin length:' 1-8, 5 2-12, 7 3-6, 5 3-9, 6 2-11, 9 3-11, 7 Depth at OD:b'd 10-12, 11 8-13, 10 12-17, 14 13-15, 14 10-14, 12 7-13, 10 Width at OD:" 5-9, 7 5-9, 6 8-12, 10 7-11, 10 6-11, 8 4-9, 6 Max. yolk depth:b 3-11, 7 1-11, 6 7-12, 10 9-16, 12 0-13, 5 0-9, 5 Max. yolk width:b 5-14, 8 1-10, 6 10-15, 12 9-18, 13 0-14, 6 0-9, 5 Flexion mesolarvae Eye diameter, % HL:a 34-38, 36 28-38, 34 32-38, 35 32-37, 34 31-38, 35 28-39, 34 AS to PV length: 75-77, 76 76-81, 79 74-79, 77 75-78, 77 75-78, 77 78-81, 79 Yolk length: 0-43, 16 0-50, 18 0-53, 26 23-54, 46 0-14, 3 0-50, 4 Depth at OD:d 8-9, 9 8-10, 9 9-12, 10 9-13, 11 10-12, 11 6-11, 9 Max. yolk depth: 0-2, 0 0-3, 1 0-7, 3 2-8, 5 0-1, 1 0-2, 0 Max. yolk width: 0-2, 1 0-4, 1 0-8, 4 1-9, 6 0-2, 0 0-5, 0 Postflexion mesolarvae Eye diameter, % HL:a 31-38, 34 24-34, 31 24-34, 28 24-35, 27 26-35, 30 27-33, 30 AS to 0P2 length: 50-53, 52 52-54, 53 53-57, 55 50-54, 53 52-56, 54 50-54, 52 e4 AS to ID length: 60-63, 62 61-64, 63 61-64, 62 62-67, 64 61-64, 62 65-67, 66 AS to PV length: 76-80, 79 78-81, 80 76-81, 79 76-80, 78 77-80, 79 78-84, 81 Dorsal fin (D) length: 4 14-16, 15 16-17, 17 11-17, 15 15-21, 18 11-15, 13 18-21, 19 Dorsal fin base length:e'4h 12-15, 13 12-14, 13 11-14, 12 12-17, 15 11-13, 12 16-18, 17 Yolk length: 0 0 0 0-7, 0 0 0 Metalarvae a Eye diameter, % HL: 28-33, 30 25-34, 30 22-27, 25 22-25, 24 25-28, 26 24-32, 27 AS to 0P2 length: 53-57, 56 54-59, 56 55-61, 58 52-57, 55 53-58, 56 51-58, 56 AS to OD length: 49-52, 50 48-53, 51 49-54, 52 47-51, 49 50-53, 51 47-51, 49 AS to ID length! 64-67, 65 61-67, 65 63-66, 64 62-67, 65 62-65, 63 65-69, 67 Caudal fin length:' 18-22, 20 16-26, 21 16-24, 21 17-25, 22 15-20, 18 20-28, 23 Dorsal fin (D) length! 18-20, 19 15-22, 19 17-21, 19 20-24, 22 15-19, 17 21-29, 24 41 Dorsal fin base length: ' 14-16, 15 12-15, 14 11-15, 13 14-17, 16 11-14, 12 16-21, 18 Juveniles <40 mm SL a Eye diameter, % HL: 27-32, 30 22-28, 25 21-28, 24 19-26, 23 22-25, 24 21-30, 25 AS to OP1 length: 25-28,26 24-29,28 23-27,25 24-28,25 24-26,25 25-31,28 AS to 0P2 length: 55-58, 56 52-59, 57 56-60, 58 52-57, 55 55-60, 57 54-60, 57 AS to OD length: 48-51, 49 48-53, 51 47-54, 51 46-49, 48 48-52, 50 46-52, 49 AS to ID length! 64-66, 65 61-68, 65 62-66, 64 61-66, 65 60-64, 63 65-70, 67 AS to PV length: • 73-76, 75 72-78, 76 72-76, 75 72-76, 74 74-78, 75 75-80, 77 Caudal fin length:' 23-28, 25 19-24, 22 20-24, 23 21-25, 23 19-23, 21 23-28, 25 Dorsal fin (D) length! 21-26, 24 18-24, 20 19-23, 21 23-26, 24 18-21, 20 23-29, 27 Dorsal fin base length:" 14-17, 16 13-16, 14 11-16, 13 14-18, 16 12-14, 13 16-20, 18 Depth at OD: 16-22, 20 17-22, 19 16-21, 19 17-22, 19 18-21, 20 18-27, 23 a Eye diameter = (AS to PE)-(AS to AE). Ignore differences in maximum values since they may be affected by developmental state at hatching. cd Ignore differences in minimum values since they may be affected by developmental state at hatching. OD for protolarvae and early flexion mesolarvae is approximated at one-half of standard length (AS to PHP). Applicable only to specimens with a full complement of dorsal fin pterygiophores or principal rays. For Xyrauchen tetanus with a rare count of only 12 or 13 principal dorsal fin rays, lengths for this character may be less than the range reported herein (all specimens analyzed for these measures had ?.14 principal dorsal fin rays or pterygiophores). Applicable only to specimens with most principal dorsal fin rays formed; ignore differences in minimum values since some data represent specimens with a few fin rays less than the adult count. Dorsal fin base = (AS to ID)-(AS to OD). Caudal fin length = (AS to PC)-(AS to PHP), total length minus standard length.

26 larvae typically has 46 to 48 total vertebrae or also useful for specific developmental inter- myomeres. The number of myomeres to the vals. Pectoral fm length is sufficiently diag- vent is typically 37 or greater for bluehead, nostic only for protolarvae, and then only flannelmouth, and razorback sucker, 37 or with respect to the maximum values for which fewer for Utah sucker, and less than 37 for it is greatest for white, mountain, and mountain sucker; white sucker larvae typically razorback suckers and least for Utah and have 35 to 38 myomeres to the vent. bluehead suc-kers. Caudal fm length is For protolarvae and flexion mesolarvae sufficiently diag-nostic only for metalarvae most diagnostically useful measures relate to and juveniles; for both intervals, caudal fm the amount of yolk remaining as the fish length is least for mountain sucker while it is grow (Table 3). By the end of the protolarva greatest for razor-back metalarvae and both phase, mountain and razorback suckers con- razorback and Utah sucker juveniles. sume most but not all of their yolk and blue- Lengths from snout to pelvic fin origin head and especially flannelmouth suckers still and posterior margin of the vent, and body retain about half of their original yolk supply depth at the origin of the dorsal fm are the by the end of the protolarva phase. All suc- only remaining length characters considered kers except some flannelmouth complete yolk sufficiently diagnostic to include in Table 3. absorption by the end of the flexion meso- Snout to pelvic fm origin lengths are appli- larva phase. cable only to postflexion mesolarvae and later For late postflexion mesolarvae, meta- intervals and, like lengths to the origin of the larvae, and juveniles most diagnostic mea- dorsal fin, are typically greatest for bluehead sures relate to the size and position of the sucker and least for flannelmouth sucker dorsal fm. The length of the dorsal fin (from metalarvae and juveniles, thereby maintaining origin of the fin to its most distal margin) and the pelvic fin origins a more-or-less similar length of the base of the fm correlate well horizontal distance behind dorsal fm origins. with the number of principal fin rays. As For postflexion mesolarvae, length to origin would be expected, these measures are great- of the pelvic fin is least for Utah sucker but est for razorback sucker and least for moun- only slightly larger for flannelmouth and tain sucker, but not much larger for bluehead razorback suckers. Snout to vent lengths are and white suckers. Length to the insertion of greatest for Utah and razorback sucker meso- the dorsal fin is also greatest for razorback larvae and razorback juveniles. and least for mountain sucker, while length to Body depth measured at the origin of the the origin of the fm is greatest for bluehead dorsal fm reflects the amount of yolk remain- sucker, followed by white and mountain suc- ing in protolarvae and mesolarvae, as noted kers, and least for flannelmouth and razor- above, but reflects the health or condition of back suckers. the fish for later stages and, especially for the Among the remaining measures, only eye larger juveniles, differences in structural diameter is useful for all developmental inter- depth. The upper end of the range for this vals. As protolarvae, mountain sucker gener- measure is notably greater for razorback ally have both the greatest eye diameters and juveniles and is probably due, at least in part, head lengths (measured to the origin of the to enlarging interneural bones behind the pectoral fin bud) relative to standard (noto- head which will eventually form the distinc- chord) length. Bluehead and flannelmouth tive predorsal "razor" or keel of older juven- protolarvae typically have the smallest eyes iles and adults. and heads. For subsequent developmental Pigmentation: Capture of these suckers intervals, differences in eye diameter are best prior to initial eye and body pigmentation is considered as a percentage of head length. rare. If not pigmented at hatching, at least For these later stages Utah sucker usually the eyes and some body pigmentation is usu- have the largest eyes while flannelmouth ally evident by emergence from the spawning sucker continue to average the smallest eyes, substrate. White and mountain suckers are although not by much. Head length among usually well pigmented by 9 mm SL and juveniles is often greatest for razorback and Utah, bluehead, and flannelmouth suckers by white suckers and least for bluehead, flannel- 11 mm SL (Table 4). Pigmentation through- mouth, and mountain suckers. out early development is generally lightest for In addition to dorsal fin lengths discussed flannelmouth and especially razorback above, pectoral and caudal fin lengths are suckers.

27 Of all pigment characters, the most diag- Once melanophore pigmentation is suffi- nostic for the later larvae and early juveniles ciently established, one of the more useful of bluehead and mountain suckers is the ex- surface pigment characters is the extent of tent of peritoneal pigmentation (Table 4). In pigmentation on the ventral midline between the ventro-lateral region of the peritoneum, the heart region and the vent (Table 5). sparse to patchy pigment is present in some White and mountain suckers typically have a postflexion mesolarvae as early as 14 or 15 continuous line of midventral pigment with mm SL and uniformly dark pigmentation is over 20 melanophores (Fig. 30-32, 34, and 72- present in all metalarvae by 20 to 22 mm SL 73), at least through the larval period. Exten- sion of this pigment line into the branchial (Figs. 45-49 and 74-77). In contrast, uniform region anterior to the heart is common in pigmentation (light or dark) in this region white sucker but rare in mountain sucker. was rare for other species. It was not obser- Among the others, only bluehead sucker ved at all for Utah sucker (Figs. 17-21) or in occasional have as many melanophores along other species less than 35 mm SL, except for the ventral midline, but the line is either rare observations of uniform light pigmenta- shorter or distinctly discontinuous (Figs. 44- tion in razorback juveniles as small as 26 mm 45). Complete absence of melanophores SL. Uniform peritoneal pigmentation also is along the ventral midline is rare among Utah, present in the ventral region of some razor- bluehead, and flannelmouth larvae but com- back juveniles as small as 29 mm SL but not mon for razorback sucker larvae. Unlike the apparent in other razorback specimens as others, razorback larvae have not been obser- large as 40 mm SL (observations through sur- ved to have more than 6 melanophores along face tissues; specimens were not dissected). the ventral midline (Figs. 85-89).

Table 4. Comparison of size (mm SL) relative to pigmental state (melanin) of eyes and bodies for protolarvae and lateral to ventral regions of the peritoneum for postflexion mesolarvae (P), metalarvae (M), and early juveniles (J, mm SL) of Upper Colorado River Basin catostomids. For peritoneal pigmentation, size is preceded by initials for the applicable developmental intervals. The letter "r" indicates that the condition is rare. Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen Character ardens commersoni discobolus latipinnis platyrhynchus texanus Eye pigmentation, protolarvaea Unpigmented 510 7 510 510 58 59 Light to moderate 9-11 7-9 9-11 9-11 8-9 7-10 Dark al° a8 al0 all a8 a9 Body pigmentation, protolarvaea Unpigmented 511 59 510 510 58 510 1-12 spots on dorsum 9-12 7-9 9-10 9-11 8-9 8-10 a13 spots on dorsum all a8 al0 all a8 a9 Peritoneal pigmentationb Lateral, P and M only Absent PM all PM 518 P 517 PM 522 P 514 PM .s24 Sparse or patchy PM al5 PM a14 PM 517 PM a19 PM 522 PM 1.14 Uniformly light M17-19 - M a21 - Uniformly dark M al7 M a21 Ventro-lateral surfaces Absent (or obscured in J) PMJ all PMJ all P 517 PMJ all PM 516 PMJ all Sparse or patchy J al9 PMJ 16-37 PM 15-17 MJ a23 PM 14-18 MJ 20-37 Uniformly light r-J 35-37 M 17-19 r-J a35 M 19-21 r-J 26-37 Uniformly dark MJ 17-23 r-J a38 MJ 20-22 r-J 35-37 Ventral surface Absent PMJ all PMJ all PM 517 PMJ all PM 521 PMJ all Sparse or patchy J 22-37 MJ 17-25 MJ a22 MJ 17-34 J 23-37 Uniformly light r-J 35-37 MJ 18-25 r-J a38 J 26-34 J a29 Uniformly dark MJ a18 r-J a38 J a26 J a32 a Some to most specimens of each species will hatch with eyes or eyes and body well pigmented. b Pigmentation of the peritoneum is subsurface and should not be confused with surface or cutaneous pigmentation. Also, pigment might be apparent in the dorsal and dorso-lateral portions of the peritoneum of smaller larvae and should not be interpreted as pigment in the lateral region. ` In juveniles, lateral pigmentation of the peritoneum usually is obscured by muscle.

28 Table 5. Comparison of the more diagnostic melanophore pigmentation patterns for larvae and juveniles (- 40 SL) of Upper Colorado River Basin catostomids. Key to characters and their states is given below. The letter "r" indicates that the character state or range of states it follows is rare.

Character Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen number ardens commersoni discobolus ladpinnis plaiyrhynchus texanus

Protolarvae (after pigment is well established) 1. 3-5 1-2 2-5 3-5 1-3 4-5 2. 1/3 1/2(r)/3 1 1 1/2(r)/3 1/2(r)/3 7. 2-3 1-2 1-3 1-3 1-2 1-3 8. 2-3 1-2 2-3 1-2 2-3 1-2 Flexion Mesolarvae 1. 3-5 1-2 2-5 3-4 1-2 4-5 2. 1/3 1-3 1 1 1-3 1-3 3. 1-2 2 1-2 1-2 2 1-2 4. 1-2 1-2 1-2 1 1-2 1-2 5. 2 2 1-2 2 1-2 2 7. 2-3 1-3 1-2 2-3 1-2 1-3 8. 1-2 1-3 1-3 1-2 2-3 1-2 9. 1 1-2 1 1-2 1 1 10. 2 2 2 2 2 1-2 11. 1-2 1-2 1-3 1-2 1 1 12. 1-2 1-2 1-2 1 1 1 13. 2-3 2-3 1-3 2-3 2-3 1-3 Postflexion Mesolarvae 1. 3(r)/4/5(r) 1/2(r) 2-3/4-5(r) 3-4 1/2(r) 4-5 2. 1/2(r)/3 1(r)/2-3 1/3(r) 1/2-3(r) 1(r)/2-3 1/2(r)/3 3. 2 2 1(r)/2 1-2 2 1(r)/2 8. 1-3 1(r)/2(r)/3 2-3 1-3 2(r)/3 1(r)/2-3 9. 1 1(r)/2(r) 1 1(r)/2 l(r) 1 12. 1-2 1-3 1-2/3(r) 1-2 1-3 1-2 13. 2(r)/3 3 2-3 2-3 2-3 2(r)/3 18. 1/2(r) 2 1/2(r) 1-2 1(r)/2 1-2(r) Metalarvae 1. 3(r)/4/5(r) 1-2 2-3/4-5(r) 3(r)/4/5(r) 1-3 4(r)/5 2. 1(r)/3 1-3 1/3(r) 1 1-3 1 3. 1(0/2 2 1-2 1-2 1(r)/2 1/2(r) 6. 1 1 1/2(r) 1 1 1 11. 3 3 3 2(r)/3 3 1(r)/2-3 12. 2(r)/3 1-2(r)/3 3 1(r)/2-3 1-2(r)/3 1/2 19. 1 1/2(r) 1 1/2(r) 1 1(r)/2 20. 1-2/3(r) 1-2/3(r) 1-2 1/2-3(r) 1/2(r) 1(r)/2 21. 1(r)/2-3 1-2/3(r) 1-2 1/2 1(0/2-3 1/2(r) Juveniles 1. 3(r)/4-5 1-3/4-5(r) 3-5 3(r)/4-5 1-2(r)/3/4(r)/5 4-5 2. 1/3(r) 1/2(r)/3 1 1 1/3(r) 1/3(r) 14. 3 2(r)/3 3 2-3 2-3 1-3 15. 2-3 1-2/3(r) 1-2 1-2 1(r)/2-3 1-2/3(r) 16. 1/2(r) 1/3 1 1 1 1 17. 1/2(r) 1-2 1 1 1/2(r) 1 19. 1-2 1-2 1 1(r)/2 1-2 2 20. 1-2/3(r) 1-2/3(r) 1(r)/2 1/2-3 1-2 1-2/3(r) 22. 1-2 1/2(r) 1 1-2 1 2

Key to pigment characters and states: 1. Ventral midline from shortly behind heart region to near vent 1. with ?/1 melanophores in a continuous or nearly continuous line or narrow band. 2. with 21 melanophores in a shorter or a distinctly discontinuous line. 3. with 7-20 melanophores. 4. with 1-6 melanophores. 5. without pigment. 2. Pigment over ventral to ventro-lateral surfaces of gill covers (opercula) 1. absent.

29 Table 5. Continued 2. present in a distinct oblique row of 3 or more melanophores near or along ventral margin of one or both preopercles. 3. present but not in distinct oblique rows. 3. Pigment on ventral surface of heart region 1. absent. 2. present. 4. Pigment under chin (anterior ventral surface of lower jaw) 1. absent. 2. present. 5. Dorsal body pigmentation between head and last myomere 1. scattered with no distinct lines of melanophores on or lateral (and parallel) to dorsal midline. 2. including at least a partial distinct line of melanophores on or lateral (and parallel) to dorsal midline. 6. Dorsal body pigmentation between head and last myomere 1. scattered more or less evenly (with or without emphasis on distinct lines of melanophores on or lateral and parallel to dorsal midline). 2. scattered but in a blotchy pattern (with or without emphasis on distinct lines of melanophores on or lateral and parallel to dorsal midline). 7. Dorsal midline from shortly behind head to near last myomeres I. with ?25 melanophores in a distinct continuous or nearly continuous line. 2. with ?25 melanophores but in one or more shorter segments or a distinctly discontinuous line . 3. with 524 melanophores in one or more short lines, a discontinuous, well-spaced line, or (rarely) with no distinct line of melanophores. 8. Dorsal surface lateral to midline from shortly behind head to about 2/3 distance to last myomeres 1. with distinct continuous or nearly continuous lines of melanophores along (parallel to) each side of dorsal midline. 2. with distinctly shorter or discontinuous lines of melanophores along one or both sides of dorsal midline. 3. without distinct lines of melanophores along either side of dorsal midline. 9. Melanophores in lines lateral (and parallel) to dorsal midline between head and 2/3 distance to last myomeres mostly 1. in single file. 2. in obliquely oriented pairs or groups resulting in a "herring bone or "tractor tread" pattern. 10. Dorsal surface of head pigmented 1. only over hindbrain (posterior to middle of eyes). 2. over both mid- and hindbrain (anterior and posterior to middle of eyes). 11. Lateral surface of body above horizontal myosepta (or lateral midline), exclusive of melanophores associated with horizontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 1. unpigmented. 2. with 1-5 melanophores. 3. with ?6 melanophores. 12. Lateral surface of body below horizontal myosepta (or lateral midline), exclusive of melanophores associated with horizontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 1. unpigmented. 2. with 1-5 melanophores. 3. with ?.6 melanophores. 13. Lateral surface of head posterior to eyes 1. unpigmented. 2. with 1-5 melanophores. 3. pigmented with ?6 melanophores. 14. Pigmentation on lateral surfaces of body above bottom-of-eye level and anterior to vent, exclusive of melanophores associated with horizontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 1. scattered only partially down to the horizontal myoseptum (lateral midline). 2. scattered fully and evenly down to the horizontal myoseptum with few if any melanophores below the myoseptum. 3. scattered evenly or in blotchy pattern (continuous with dorsal and dorso-lateral surface pattern) down to horizontal myoseptum and at least partially to bottom- of-eye level below. 15. Pigmentation on lateral to ventro-lateral surfaces of body below bottom-of-eye level, exclusive of melanophores associated with horizontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 1. absent including caudal peduncle. 2. absent except on caudal peduncle. 3. present. 16. Lateral surface of body 1. with no large, distinct, mid-lateral body spots. 2. with 2 large, distinct mid-lateral body spots, one between head and dorsal fin and the other between pelvic and anal fins. 3. with 3 large, distinct mid-lateral body spots, one between head and dorsal fin, the second between pelvic and anal fins, and the last on the caudal peduncle near the base of the tail. 17. Pigment outlining scales 1. absent or light. 2. bold.

30 Table 5. Continued 18. Developing dorsal fin 1. with few (s5) or no melanophores. 2. with many (?6) melanophores. 19. Pigment in dorsal fin 1. along fin rays with very few, if any, melanophores on membrane between rays. 2. abundant both along and between rays. 20. Pigment in anal fin 1. absent. 2. present but very light with only a few (55) melanophores. 3. present but more prominent with many (?..6) melanophores. 21. Pigment in pectoral fin 1. absent. 2. present but very light with only a few (s5) melanophores. 3. present but more prominent with many (a•6) melanophores. 22. Pigment in caudal fin 1. along fin rays with very few, if any, melanophores on membrane between rays. 2. abundant both along and between rays.

Presence and pattern of melanophores on Among juveniles, only white sucker and some the ventral to ventro-lateral surfaces of the Utah sucker display large mid-lateral spots. gill covers can also be diagnostic throughout White sucker have three spots (Fig. 35) while the early development of these fishes. Such Utah sucker with lateral spots have only two pigment is present on some larvae of all distinct spots anterior to the vent (a faint or developmental intervals for all species except indistinct third lateral spot might be apparent bluehead and flannelmouth sucker. It is in the caudal region of some Utah suckers). rarely present on bluehead flexion mesolarvae The scales of most white sucker and some and metalarvae or on flannelmouth flexion Utah and mountain suckers greater than 30 mesolarvae. Distinct oblique rows of three or mm SL are well outlined with pigment (Fig. more melanophores are often present along 35). or near the ventral margin of the preopercle Distribution of pigment in various fins of white and mountain suckers (Figs. 31 and can be diagnostic for later larvae and juven- 74), but are rarely present for most other iles. Pigment along the rays of the dorsal and species. caudal fins is typical of all suckers considered Another obvious diagnostic character for herein. In addition, abundant melanophores protolarvae and mesolarvae is the melano- on the membranes between dorsal and caudal phore pattern of the dorsal surface from fm rays are characteristic of all razorback behind the head to about two-thirds the juveniles (Fig. 91) and most razorback meta- distance to the last myomeres. Pigment here larvae. In contrast, few melanophores are tends to be scattered with no distinct lines present on the membranes between caudal parallel to the dorsal midline for mesolarvae fin rays of bluehead and mountain sucker of most bluehead and mountain suckers metalarvae and juveniles, dorsal fm rays of (Figs. 44-45 and 72-73). Many flannelmouth bluehead, mountain and Utah sucker meta- and some white sucker mesolarvae have lines larvae, and dorsal fin rays of bluehead of melanophores lateral to the dorsal midline juveniles. in which the melanophores tend to be in obliquely oriented pairs or groups resulting in a Mouth characters are important in the distinctive "herring bone" or "tractor tread" diagnosis of adult catostomids. Unfortunately pattern (Figs. 30 and 58). the mouths are insufficiently developed in all Extent of lateral body pigmentation is but the latest larvae and certain characters useful for mesolarvae through juveniles. remain indistinct in the earliest juveniles (e.g., Among flexion mesolarvae, for example, at the lower lip lobes of some bluehead suckers least a couple melanophores are sometimes up to 25 mm SL, Table 6). present between dorsolateral surface and the Mouth position remains terminal for horizontal myoseptum of all but flannelmouth some metalarvae and juveniles of mountain and razorback suckers. Even by the metalar- and razorback suckers up to 25 mm SL, but val phase, some razorback sucker are still changes to low terminal or subterminal by 19 without pigment in this region (Fig. 88). mm SL for all metalarvae of the other

31 species. Some white, flarmelmouth, and mountain suckers, the notches are present razorback suckers have low terminal mouths and separate the upper and lower lips (Figs. throughout the metalarval phase and early 48 and 49). For the other species, distinct juvenile period, at least up to 40 mm SL notches are not present and the upper and (Figs. 90 and 91). The first subterminal lower lips are more-or-less smoothly joined mouths appear as early as 18 mm SL for (Figs. 62 and 63). bluehead metalarvae and as late as 32 mm SL Osteological features can be conclusively for razorback juveniles. All bluehead sucker diagnostic for late metalarvae and juveniles juveniles and metalarvae over 19 mm SL have of razorback sucker, subgenus Pantosteus, and subterminal mouths (Figs. 47-49). Likewise for all mountain sucker greater than 25 mm subgenus Catostomus. Unfortunately these SL and Utah sucker larger than 31 mm SL. characters, as well as vertebra counts discussed under meristics, require that speci- The median cleft of the lower lip divides mens be cleared and preferably stained for the lip of these suckers into two distinct bone (or that the structures of interest be lobes. The cleft is deep in most suckers but otherwise exposed). They are therefore best is shallow in bluehead and mountain suckers used to confirm or refine identities based on in which it is bridged by a few rows of more external characters for which special papillae. Once the lower lips are sufficiently preparation is not required. The fronto- formed to distinguish two lobes, the lower lip parietal fontanelle (opening between the lobes of most metalarvae and some juveniles frontal and parietal bones covered with con- of all species are well separated. This separ- nective tissue) and first interneural bone are ation continues for some Utah, white, and observable in some late postflexion meso- bluehead sucker up to 25 to 31 mm SL (Figs. larvae while the remaining skeletal characters 47 and 48), some razorback suckers up to at considered are applicable only to larger least 37 mm SL, and many mountain suckers metalarvae and juveniles (Fig. 6). Adult to at least 40 mm SL (Figs. 75-77). The gap descriptions suggest that more detailed study closes much more rapidly for flannelmouth of larval and early juvenile skeletons might sucker with all specimens over 20 mm SL reveal additional skeletal differences, but having either adjacent or slightly separated these are probably the more obvious. lip lobes (Figs. 61-63). Metalarvae of neither As the bones of the skull form, an oval mountain nor bluehead sucker have adjacent to rectangular fontanelle approximately half or only slightly separated lip lobes; only their as wide as long forms in postflexion meso- juveniles have these traits. larvae and small metalarvae. By 20 mm SL, The presence or absence of notches at the fontanelle narrows to a rectangular shape the corners of the mouth is diagnostic for and maximum width less than 45% of maxi- juveniles as well as adults. For bluehead and mum length for all but razorback sucker

TABLE 6. Comparison of size (mm SL) relative to mouth position and lower lip lobe separation for metalarvae (M) and juveniles (J, mm SL) of Upper Colorado River Basin catostomids. Size is preceded by initials for the applicable developmental intervals; "r" indicates that the condition is rare.

Catostomus Catostomus Catostomus Catostomus Catostomus Xyrauchen Character ardens commersoni discobolus latipinnis platyrhynchus texanus

Mouth position Terminal, above bottom of eye M 519 M 18 M 17 MJ 25 MJ 25 Low terminal, at or below bottom of eye MJ 531 MJ all M MJ all MJ 25 MJ all SUBTERMINAL, low and not most anterior portion of snout J ?23 J ?19 MJ.?18 MJ 22 J ?23 J ?32

Lower lip lobes, median separation

Indistinct M 518 M 518 MJ 525 M 522 Well separated MJ 525 MJ 531 MJ 528 M20 MJ all MJ 537 Slightly separated MJ A.18 MJ 17-31 J ?.22 MJ all J 1.23 MJ 20-37 None, adjacent J .22(R) MJ 17 J 22 MJ ?.22 J 1.26(R) MJ 20

32 (Table 7, Fig. 7). Beyond 20 mm SL, fontan- tam n suckers. Smith (1966) reported that the elle length increases proportionately with fontanelle of bluehead sucker is usually body length, but width and shape vary with reduced in juveniles and closed in adults, species. Width generally increases in razor- while that of mountain sucker adults is usu- back sucker and maintains a more-or-less ally reduced to a narrow slit but occasionally oval shape, decreases in mountain sucker, and obliterated. To document, preliminarily, remains relatively constant in the others changes in fontanelle shape and size toward (greatest in Utah sucker and least in blue- the adult condition, we cleared and stained head sucker). For specimens 35-46 mm SL, one 76 to 81 mm SL yearling for each species fontanelle width remains greater than 45% except Utah sucker (specimen not available). of length in most razorback sucker (rarely as Based on these solitary observations (Table low as 43%), drops to less than 25% in 7), the fontanelle continues to grow in both mountain sucker, and ranges between 25 and length and width in razorback sucker and 45% in the others (generally lowest in blue- maintains its larger width-to-length ratio head sucker). Observations for Utah sucker (45%). The fontanelle increases significantly may be suspect due to poor culture condi- only in length for white, flannelmouth, and tions and growth rates (Appendix C, Snyder bluehead suckers, resulting in decreased and Muth 1988). width-to-length ratios (25-26% for white and Adult descriptions of the subject species flannelmouth and 19% for bluehead sucker). reveal that the fontanelle is significantly Only in mountain sucker was the fontanelle reduced or lost only in bluehead and moun- closed. More yearling and older specimens

Table 7. Comparison of frontoparietal fontanelle s ize for selected length groups of larval and juvenile catostomids of the Upper Colorado River Basin. " N" is number of specimens examined.

Size group Catostomus Catostonzus Catostomus Catostomus Catostomus Xyrauchen Character ardens comnzersoni discobolus latipinnis platyrhynchus texanus

17-19 mm SL, n 2 2 4 3 0 3 Width, mm 1.0-1.2 0.8-1.0 0.6-0.9 0.8-1.2 1.0-1.2 Length, mm 2.0-2.2 2.0-2.2 1.4-1.8 1.2-2.0 1.7-1.9 Width/length, % 45-60 40-45 41-50 50-67 59-63

20-21 mm SL, n 1 2 2 3 2 5 Width, mm 0.9 0.6-0.8 05-0.9 0.6-0.7 0.6-0.8 1.0-1.3 Length, mm 2.1 1.9-2.1 1.7-1.7 1.8-2.0 2.2-2.2 1.8-2.1 Width/length, % 43 32-38 29-35 33-35 27-36 52-68

22-25 mm SL, n 2 1 3 3 1 2 Width, mm 0.9-0.9 0.8 0.5-0.8 0.8-0.8 0.7 1.0-1.3 Length, mm 2.3-2.4 2.0 1.3-2.8 1.8-2.1 2.2 1.9-2.1 Width/length, % 38-39 40 29-38 38-44 32 53-62

26-34 mm SL, n 3 2 2 2 1 2 Width, mm 1.0-1.0 0.8-0.8 0.6-0.7 0.7-0.8 05 0.9-1.3 Length, mm 2.3-2.4 2.3-2.6 2.0-2.2 2.2-2.3 2.1 2.1-2.3 Width/length, % 42-43 31-35 27-35 30-36 24 43-57

35-46 mm SL, n 1 1 1 1 2 3 Width, mm 1.1 0.9 0.7 0.7 0.4-0.5 1.1-1.7 Length, mm 2.7 3.0 2.7 2.3 25-2.7 2.3-3.4 Width/length, % 41 30 26 30 15-20 48-50

All 2246 mm SL, n 6 4 6 6 4 7 Width, mm 0.9-1.1 0.8-0.9 05-0.8 0.7-0.8 0.4-0.7 0.9-1.7 Length, mm 2.3-2.7 2.0-3.0 1.3-2.8 1.8-2.3 2.1-2.7 1.9-3.4 Width/length, % 38-43 30-40 26-38 30-44 15-32 43-62

76-81 mm SL, n 0 1 Width, mm 0.8 0.7 1.0 0.0 2.3 Length, mm 3.1 3.7 4.0 0.0 5.1 Width/length, % 26 19 25 0 45

33 For juveniles and metalarvae greater than 22 mm SL, the anterior margins of the mandibles are closer to the posterior ends of the maxillae in bluehead and mountain suckers (Fig. 9). For the other species, they are closer to the anterior ends of the maxillae. However, by about 40 mm SL, at least some flannelmouth suckers have anterior margins

Fig. 7. Frontoparietal fontanelles of early juveniles. Top — Xyrauchen texanus; wide and oval. Bottom — Catostomus species; moderately wide to narrow and rectangular. must be examined to determine if fontanelle closure is typical of mountain sucker populations in the Upper Colorado River Basin. The large, fan-shaped, first interneural bone of razorback sucker metalarvae and juveniles over 16 mm SL readily distinguishes it from the other species (Fig. 8). By late in the metalarval phase, the smaller interneurals posterior to the first also develop enlarged or flared tops. The interneurals eventually form the skeletal basis for the unique predorsal keel or "razor" of the razorback sucker (Fig. 94). By 20 mm SL, the first interneural also segregates the remaining species according to subgenera. Subgenus Catostotnus (Utah, white, and flannelmouth suckers) have moderate to large, anvil-shaped first interneurals with moderate to long posterior extensions (especially long in flannelmouth Fig. 8. Interneural bones of late metalarvae and early juveniles. Top — Xyrauchen texanus; first interneural sucker). Subgenus Pantosteus (bluehead and large and fan-shaped; posterior inter-neurals well mountain suckers) have smaller, somewhat formed and flared dorsally. Middle — subgenus blocky first interneurals with short to Catostomus; first interneural moderate to large, anvil- shaped with prominent posterior extension. Bottom moderate posterior extensions. — subgenus Pantosteus; first interneural smaller and Position of mandibles relative to maxillae more blocky with short to moderate posterior projec- also are diagnostic for subgenus Pantosteus. tion.

34 0 teus, about 90 for bluehead and mountain suckers and variable, but usually much less for the others (Fig. 11). However, the differences in this character are not always distinct, and perceived postcleithral angle can be affected strongly by angle of view. This character needs further study.

Fig. 9. Position of mandibles relative to maxillae of late metalarvae and only juveniles. Top Xyrauchen texanus and subgenus Catostomus; anterior ends of mandibles far anterior to posterior ends of maxillae. Bottom — subgenus Pantosteus; anterior ends of mandibles slightly anterior to posterior ends of maxillae. of the mandibles positioned about midway between anterior and posterior ends of the maxillae. Shape and size of anterior-dorsal projections on the maxillae are diagnostic for razorback sucker and subgenus Pantosteus greater than 22 mm SL, sometimes smaller. The anterior-dorsal projections of the maxillae are very shallow to almost absent in razorback sucker, relatively long and pointed (at least as deep as wide at the base) in bluehead and mountain suckers, and intermediate (prominent but blunt and less deep than wide at the base) in subgenus Catostomus (Fig. 10). Fig. 10. Anterior-dorsal maxillary projections of late metalarvae and early juveniles. Top -- Xyrauchen The angle at which the postcleithrum texanus; very shallow to flat. Middle -- subgenus extends from the cleithrum was initially sus- Catostomus; short and blunt. Bottom -- subgenus pected to be diagnostic for subgenus Pantos- Pantosteus; long and more pointed.

35 Fig. 11. Postcleithra of late metalarvae and early juveniles. Top -- Xyrauchen texanus and subgenus Catostomus; postcleithrum base often extends from 0 cleithrum at much less than 90 angle. Bottom -- subgenus Pantosteus; often extends from cleithrum 0 at about 90 angle.

36 Keys -- Upper Colorado River Basin keys, melanophores refer only to those with Catostomids visible pigment (other melanophores may be present but lack pigment or sufficient amounts to be obvious under low power The continual change in available char- magnification). acters and character states and similarity of species during larval and early juvenile These keys require the use of a low- development are accommodated by separate power microscope and some means of keys for eggs, each of four larval phases, and measuring to the nearest 0.1 mm, e.g., early juveniles up to 40 mm SL (about 50 mm pointed dial calipers, graduated mechanical TL). Users must begin by determining the stage, or measuring eyepiece reticle with a developmental interval of the specimen in stage micrometer disc or slide for calibration. question: embryo (egg), protolarva, flexion If using the latter, be sure to set focus before mesolarva, postflexion mesolarva, metalarva, calibration; any subsequent changes in focus or early (young-of-the-year) juvenile -- see or magnification will require recalibration. If preceding section on developmental interval using a zoom microscope and eyepiece reti- terminology for complete definitions. Users cle, the scale can be calibrated for direct must then determine standard length since millimeter measurement. A 10 mm reticle each key begins with size dependent charac- scale in a 10X eyepiece focused on the speci- ers. Although the polychotomous keys are men (or stage micrometer) with precisely 1X necessarily long and complex, often with of objective magnification will measure 10 multiple paths leading to the same conclu- mm (note that zoom control magnification ion, most specimens will require no more scales may not be accurate). At 0.5X objec- than several steps to reach a terminus. tive magnification, the reticle scale will Supplemental keys based on selected skeletal measure 20 mm (each 0.1 division then characters are provided to confirm or better equals 0.2 mm). If the specimen is not too large, adjustment of magnification to calibrate resolve the identity of postflexion mesolarvae, metalarvae and juveniles (specimens must be the reticle scale to standard length (Fig. 4) of cleared and preferably stained). the specimen will allow direct measurement of specific structures or dimensions as a A discussion of characters useful in iden- percentage of standard length. tification of cypriniform larvae and diagrams of anatomical features, methods of counts Except for fm lengths, measurements are and measures, gut loop phases, and selected made parallel or perpendicular to the body skeletal structures (Figs. 2-6) precede results. axis (Fig. 4). Specimens must be completely The discussion of cypriniform characters submerged in fluid (usually water) and posi- includes criteria for distinguishing the families tioned such that their body axis is horizontal. Cyprinidae and Catostomidae (see especially Flat pieces of glass can be used to prop or fins and finfolds, last paragraph on myo- hold-down a specimen. For fish which taper meres, and fifth paragraph on morphology). from head to tail or have a pectoral fm pre- A comparative summary of diagnostic charac- venting it from lying flat on the bottom of a dish, try suspending the head and part or ters and species accounts immediately precede and follow this section, respectively. most of the body over the edge of a suffi- The species accounts include full sets of ciently thick piece of glass. Lay another, dorsal, lateral, and ventral view drawings. smaller and thinner piece of glass over the Users of the keys should be familiar with this tail to hold the specimen in position. Curved material before proceeding. or bent specimens that can't be straightened or gently flattened under a cover slip or The drawings in the species accounts are thicker piece of glass can be measured in frequently referenced in the keys, especially sections along the horizontal axis. Specimens to illustrate specific patterns of melanophore larger than the range of the measuring devise pigmentation. However, referenced figures also can be measured in sections. Measure- are Ilia necessarily of the species, development units are the nearest whole or tenth of mental state, or size appropriate to the a millimeter (e.g., a 12 mm specimen covers portion of the key in which the reference is the range 11.50 to 12.49 mm, and a measure made. Each spot of black or brown pigment of 6.5 more precisely measures between 6.450 (melanin) represents a melanophore. In the and 6.549).

37 Some keys require myomere counts 3 and 4). Principal dorsal and anal fin rays (lateral muscle segments; Fig. 3-4). For include all branched rays and the long accurate counts, the first myomere must be unbranched ray preceding them. Principal identified and included. It is partial (epa)dal, caudal rays include all branched rays and the dorsal only), sometimes deltoid or triangular long unbranched rays immediately above and in shape, and located above and often slightly below them. Terminal branching for some anterior to the cleithrum or base of the principal rays of the dorsal and anal fins pectoral fin (Fig. 4). To observe myomeres, might not be evident until late in the meta- experiment with both reflected (from above) larval phase, but the pterygiophores asso- and transmitted (from beneath) light. For ciated with them are obvious on close exa- small, somewhat translucent specimens, bright mination. The most posterior principal ray transmitted light will pass through the larva for dorsal and anal fins consists of two and make myomeres more visible. In many elements that articulate with the last ptery- cases, the addition of a pair of polarizing giophore. By convention, these elements are filters will actually highlight individual said to branch at the base and are counted myomeres, including the first. One polarizing together as one principal ray. In early meta- lens is placed between the light source and larvae, the most posterior element of the last specimen (under the dish) and the other is ray is often difficult to observe. Again, rely positioned or held between the specimen and on the association between principal dorsal the objective lens of the microscope. The and anal fin rays and their pterygiophores to highlighting effect is achieved by rotating the confirm counts. All fin rays are included in upper lens until the background is black or as pectoral and pelvic fin ray counts. Do not dark as possible. Only light waves that are mistake the spine-like pelvic splint at the turned 90° as they pass through the larva are leading edge of the pelvic fin for a fin ray. observed. The position of the specimen rela- Transmitted light and polarizing filters are tive to the plane of light passed by the lower useful in observing pterygiophores and fm filter is important as well. Once background rays. light is minimized, rotate the specimen itself, or the dish, for optimal effect. For larger or Keys are seldom perfect. When a speci- more opaque specimens, reflected light at a men is near the boundary between develop- low to near-horizontal angle casts shadows mental phases, use the adjacent key to help that help define myomeres. confirm results of the proper key. Similarly, within keys, if a character state is nearly Fin ray counts also are required for some borderline or if the user is unsure which of keys. Developing fm rays must not be confused with folds or creases in the finfold or the criteria the specimen meets, try both branches of the key. In either of these situ- membrane, or with the skeletal structures ations, if the conclusions are different, and that precede and support median fin rays, i.e., the hypural elements of the caudal fm and remain so after review, either the identity via pterygiophores of the dorsal and anal fins the more appropriate key or branch should (Fig. 3). The hypural elements eventually be considered tentative (add a question mark, "?", fuse and form the hypural plates. Externally, to the name and footnote other possibili- the upper or articulating ends of pterygio- ties) or the identity of the specimen should be left in question (label to family or genus phores appear as small nodules at the base of the developing dorsal and anal fins. Since only). When character states are so similar between species that positive diagnosis is not pterygiophores appear before the rays they possible (based on characters studied), the support and since there is a one to one keys conclude with two or more possible correspondence between pterygiophores and principal fm rays, pterygiophore counts can species. As previously noted, some of these substitute for principal dorsal and anal fm specimens might be hybrids. Use both the comparative summary and species accounts counts near the end of the mesolarval phase. to help confirm conclusions reached through Also use them to determine presence of all these keys. Non-morphological data, such as principal dorsal or anal rays (a requirement for transition to the metalarval phase). collection date and location, can be used sometimes to delimit possible species (e.g., For median fins, principal rays also must neither Utah, white, nor razorback sucker be distinguished from rudimentary rays (Figs. have been reported in the White River in

Colorado -- Snyder 1981, Tyus et al. 1982). val drift or migration, nursery habitat, and However, such data must be used cautiously. sometimes species distribution. The authors Positively identified fish larvae are often the appreciate notification of errors, misleading basis for revision of previous assumptions criteria, or problems uncovered by users, as regarding spawning seasons and grounds, lar- well as suggestions for revisions.

Eggs -- water hardened (embryos with pigment- C. platyrhynchus ed eyes can be removed from the chorion X. texanus and further identified using the key for d. 2.8 mm C. commersoni X. texanus protolarvae). e. 2.9-3.2 mm C. ardens C. commersoni 1. Diameter (maximum) f. 3.3 mm C. commersoni a. 2.3-2.4 mm C. platyrhynchus C. discobolus platyrhynchus b. 2.5 mm C g. 3.4-3.6 mm C. discobolus X. texanus h. 3.7-3.9 mm C. latipinnis c. 2.6-2.7 mm C commersoni

Protolarvae -- no caudal fin rays (definition b. lightly to moderately pigmented (Figs abbreviated for species of concern; Figs. 3, 70, 84) 142 4, 14, 15) c. darkly pigmented (Fig. 71) 6 6 (5). Body 1. Standard (notochord) length (SL; Fig. 4) a. unpigmented to sparsely pigmented, 512 a. 7 mrn 2 melanophores (spots of black or brown b. 8 mm 4 pigment) on dorsal surface (Fig. 70) . . . 93 c. 9 mm 7 b. moderately to well pigmented, L-13 d. 10 mm 12 melanophores on dorsal surface (Fig. e. 11 mm 15 71) 24 f. 12 mm 19 g. 13 mm 21 7 (1). Yolk a. present ...... 8 2 (2). Eyes b. absent ...... X. texanus a. unpigmented C. ardens C. commersoni 8 (7). Pectoral fin buds C. platyrhynchus a. absent ...... C. latipinnis X. texanus b. present (Figs. 70, 84) initially form as b. lightly to moderately pigmented (Figs. minute crescents high on anterior sur- 70,84) ...... 3 face of yolk sac and are later above and anterior to yolk sac) 9 3 (2). Body 9 (8). Eyes a. unpigmented (Fig. 84) 129 a. unpigmented C. ardens b. sparsely pigmented, 5.12 melanophores C. commersoni (spots of black or brown pigment) on C. discobolus dorsal surface (Fig. 70) . . . . C. commersoni C. latipinnis C. platyrhynchus 4 (1). Pectoral fin buds X. texanus a. absent ...... C. discobolus C. latipinnis b. lightly to moderately pigmented (Figs. 70, 84) 10 b. present (Figs. 70, 84; buds initially form 11 as minute crescents high on anterior c. darkly pigmented (Figs. 71, 85) surface of yolk sac and are later above 10 (9). Body and anterior to yolk sac) ...... 5 a. unpigmented (Fig. 84) 122 b. sparsely pigmented, 512 melanophores 5 (4). Eyes (spots of black or brown pigment) on a. unpigmented C ardens dorsal surface (Fig. 70) 132 C. discobolus C. platyrhynchus 11 (9). Body X. texanus a. unpigmented (Fig. 84) 129

39 b. sparsely pigmented, melanophores a. with melanophores in a distinct con- (spots of black or brown pigment) on tinuous or nearly continuous line (Figs. dorsal surface (Fig. 70) 142 43, 71) (rarely) C. latipinnis c. moderately to well pigmented, ?_-13 b. with L-25 melanophores but in a shorter melanophores on dorsal surface (Figs. or distinctly discontinuous line or with 71, 85) 25 melanophores (Figs. 15, 57) 22

12 (1). Yolk 22 (21). Dorsal surface lateral to midline from a. present ...... 13 shortly behind head to about 2/3 b. absent ...... 26 distance to last myomeres a. with distinct continuous or nearly con- 13 (12). Eyes tinuous lines of melanophores along a. unpigmented C ardens (parallel to) each side of dorsal mid- C. discobolus line (Fig. 57) C. latipinnis C. latipinnis b. with distinctly shorter or discontinuous b. lightly to moderately pigmented (Figs lines of melanophores along one or both 14, 84) 114 sides of dorsal midline (Fig. 15) 23 c. darkly pigmented (Figs. 15, 85) 14 C. without distinct lines of melanophores along either side of dorsal midline (Fig. 14 (13). Body 85) C. ardens a. unpigmented to sparsely pigmented, 5.12 melanophores (spots of black or brown 23(22). Pigment on ventral to ventro-lateral pigment) on dorsal surface (Fig. 70) . . 81 surfaces of gill covers (opercula) b. moderately to well pigmented, L-13 a. absent (Figs. 15, 57) 120 melanophores on dorsal surface (Figs. b. present (Figs. 16, 17) C. ardens 71, 85) 25 24 (6). Ventral midline from shortly behind 15 (1). Yolk heart region to near vent a. present ...... 16 a. with L-13 melanophores in a continuous b. absent ...... 26 or nearly continuous line or narrow band, or in a shorter or distinctly dis- 16 (15). Eyes continuous line (if L-21 melanophores on a. lightly to moderately pigmented (Fig midline from heart to vent and pigment 14) 17 line extends into branchial region, anter- b. darkly pigmented (Figs. 15) 18 ior to heart, most probably C. commersoni -- Fig. 31) (Figs. 29, 71) 38 17 (16). Body b. with 7-12 melanophores (Fig. 43) a. unpigmented (Fig. 14) C. ardens C platyrhynchus b. sparsely pigmented, .. 12 melanophores (spots of black or brown pigment) on 25 (11,14). Ventral midline from shortly behind dorsal surface (Fig. 70) 120 heart region to near vent a. with L-13 melanophores in a continuous 18 (16). Body or nearly continuous line or narrow a. unpigmented (Fig. 14) C ardens band, or in a shorter or distinctly dis- b. sparsely pigmented, -.12 melanophores melanophores on (spots of black or brown pigment) on continuous line (if dorsal surface (Fig. 70) 120 midline from heart to vent and pigment branchial region, anter- c. moderately to well pigmented, -13 line extends into commer- melanophores on dorsal surface (Figs. ior to heart, most probably C. soni -- Fig. 31) (Figs. 29, 71) 38 15,71) ...... 34 b. with 7-12 melanophores (Fig. 43) platyrhynchus 19 (1). Yolk C c. with .54.6 melanophores (Fig. 85) texanus a. present ...... 20 X. b. absent ...... X. texanus 26 (12,15). Ventral midline from shortly behind 20 (19). Body heart region to near vent a. sparsely pigmented, .. 12 melanophores a. with .>_-7 melanophores (Fig. 71) (spots of black or brown pigment) on C. platyrhynchus dorsal surface (Fig. 70) C. ardens b. with -1-6 melanophores (Fig. 85) X. texanus b. moderately to well pigmented, L-13 melanophores on dorsal surface (Figs. 27 (20). Ventral midline from shortly behind 15, 71) 27 heart region to near vent a. with >. 21 melanophores in a continuous 21 (1). Dorsal midline from shortly behind head or nearly continuous line or narrow to near last myomeres band (Fig. 30) C. commersoni

40 b. with ?_-.21 melanophores in a shorter or (if ventral midline from heart to vent distinctly discontinuous line (Fig. 44) . . . 28 extends into branchial region, anter- c. with melanophores (Figs. 15, 43, ior to heart, most probably C. corn- 57) 31 mersoni -- Fig. 31) (Fig. 30) 38 b. with ?-21 melanophores in a shorter or 28 (27). Pigment on ventral to ventro-lateral distinctly discontinuous line (Fig. 71) . • 35 surfaces of gill covers (opercula) c. with 7 to 20 melanophores (Fig. 43) . . • 39 a. absent (Fig. 43) 29 d. with Is6 melanophores (Fig. 85) 45 b. present (Figs. 29, 30) C commersoni 35 (34). Pigment on ventral to ventro-lateral 29 (28). Dorsal surface lateral to midline from surfaces of gill covers (opercula) shortly behind head to about 2/3 a. absent (Figs. 43, 71) 36 distance to last myomeres b. present (Figs. 29, 30) 38 a. with distinct continuous or nearly continuous lines of melanophores along (paral- 36 (35). Dorsal surface lateral to midline from lel to) each side of dorsal midline (Fig. shortly behind head to about 2/3 30) C. commersoni distance to last myomeres b. with distinctly shorter or discontinuous a. with distinct continuous or nearly contin- lines of melanophores along one or both uous lines of melanophores along (paral- sides of dorsal midline (Figs. 43, 85) . . . 30 lel to) each side of dorsal midline (Fig. c. without distinct lines of melanophores 30) C. commersoni along either side of dorsal midline (Figs. b. with distinctly shorter or discontinuous 44, 71) C. discobolus lines of melanophores along one or both sides of dorsal midline (Figs. 43, 72) . . . 37 30 (29). Dorsal midline from shortly behind c. without distinct lines of melanophores head to near last myomeres along either side of dorsal midline (Figs. a. with melanophores in a distinct con- 44, 71) 43 tinuous or nearly continuous line or in a shorter or distinctly discontinuous line 37 (36). Dorsal midline from shortly behind (Figs. 30, 31, 43) 60 head to near last myomeres b. with melanophores (Fig. 85) a. with ?_-25 melanophores in a distinct con- C. discobolus tinuous or nearly continuous line or in a shorter or distinctly discontinuous line 31 (27). Pigment on ventral to ventro-lateral (Figs. 43, 71) 87 surfaces of gill covers (opercula) b. with s24 melanophores (Fig. 85) a. absent (Figs. 15, 43, 57) 32 C. discobolus b. present (Figs. 16, 17) C ardens 38 (24,25,34,35). Dorsal surface lateral to mid- 32 (31). Dorsal surface lateral to midline from line from shortly behind head to shortly behind head to about 2/3 about 2/3 distance to last myomeres distance to last myomeres a. with distinct continuous or nearly contin- a. with distinct continuous or nearly continuous lines of melanophores along (paral- uous lines of melanophores along (parallel to) each side of dorsal midline (Fig. lel to) each side of dorsal midline (Fig. 30) C. commersoni 57) C. latipinnis b. with distinctly shorter or discontinuous b. with distinctly shorter or discontinuous lines of melanophores along one or both lines of melanophores along one or both sides of dorsal midline (Fig. 72) or with- sides of dorsal midline (Figs. 15, 43, out distinct lines of melanophores along 85) 33 either side of dorsal midline (Figs. 29, c. without distinct lines of melanophores 71) 93 along either side of dorsal midline (Figs. 44,71) ...... 48 39 (34). Pigment on ventral to ventro-lateral surfaces of gill covers (opercula) 33 (32). Dorsal midline from shortly behind a. absent (Figs. 15, 43, 57, 71) 40 head to near last myomeres b. present (Fig. 16) 44 a. with L-25 melanophores in a distinct continuous or nearly continuous line (Fig 40 (39). Dorsal surface lateral to midline from 43) 113 shortly behind head to about 2/3 b. with L-25 melanophores but in a shorter distance to last myomeres or distinctly discontinuous line or with a. with distinct continuous or nearly contin- melanophores (Figs. 15, 57) 73 uous lines of melanophores along (parallel to) each side of dorsal midline (Fig. 34 (18). Ventral midline from shortly behind 57) C. latipinnis heart region to near vent b. with distinctly shorter or discontinuous a. with 2-.21 melanophores in a continuous lines of melanophores along one or both or nearly continuous line or narrow band sides of dorsal midline (Figs. 15, 43) . . . 41

41 c. without distinct lines of melanophores a. with 2:25 melanophores in a distinct con- along either side of dorsal midline (Figs. tinuous or nearly continuous line (Fig 44, 71) 42 71) 102 b. with melanophores but in a shorter 41 (40). Dorsal midline from shortly behind or distinctly discontinuous line or with head to near last myomeres melanophores (Figs. 15, 85) 114 a. with a.25 melanophores in a distinct continuous or nearly continuous line (Fig. 48 (32,46). Dorsal midline from shortly behind 43) 97 head to near last myomeres b. with L-25 melanophores but in a shorter a. with L-25 melanophores in a distinct con- or distinctly discontinuous line (Fig. 15) tinuous or nearly continuous line (Fig. 105 71) C. discobolus c. with melanophores (Fig. 57) 73 b. with melanophores but in a shorter or distinctly discontinuous line or with 42 (40). Dorsal midline from shortly behind melanophores (Figs. 45, 85) 51 head to near last myomeres a. with ?-25 melanophores in a distinct 49 (45). Dorsal surface lateral to midline from continuous or nearly continuous line shortly behind head to about 2/3 (Fig. 71) 64 distance to last myomeres b. with melanophores but in a shorter a. with distinct continuous or nearly con- or distinctly discontinuous line (Fig. tinuous lines of melanophores along 45) 76 (parallel to) each side of dorsal midline c. with 152. 4 melanophores (Fig. 85) 51 (Fig. 57) X. texanus b. with distinctly shorter or discontinuous 43 (36). Dorsal midline from shortly behind lines of melanophores along one or both head to near last myomeres sides of dorsal midline (Figs. 15, 85) . . . 50 a. with L-2.5 melanophores in a distinct con- c. without distinct lines of melanophores tinuous or nearly continuous line or in a along either side of dorsal midline (Fig. shorter or distinctly discontinuous line 71) C. ardens (Figs. 45, 71) 64 b. with melanophores (Fig. 85) 50 (49). Dorsal midline from shortly behind C. discobolus head to near last myomeres a. with melanophores in a distinct continuous or nearly continuous line (Fig. 44 (39). Dorsal midline from shortly behind 43) X. texanus head to near last myomeres b. with ?:25 melanophores but in a shorter a. with L-25 melanophores in a distinct con- or distinctly discontinuous line or with tinuous or nearly continuous line (Fig. melanophores (Figs. 15, 85) 56 71) C platyrhynchus b. with ?:25 melanophores but in a shorter 51 (42,48). Length from anterior margin of or distinctly discontinuous line (Fig. snout to posterior margin of eye 15) 54 a. 6-8% SL 52 c. with melanophores (Fig. 85) . C. ardens b. 9% SL C. ardens

45 (34). Pigment on ventral to ventro-lateral 52 (51). Number of myomeres to posterior surfaces of gill covers (opercula) margin of vent a. absent (Figs. 15, 43, 57, 85) 46 a. 35-36 C. ardens b. present (Figs. 16, 17) 49 b. 37-39 53 c. 40-41 C. discobolus 46 (45). Dorsal surface lateral to midline from shortly behind head to about 2/3 53 (52). Length from anterior margin of snout distance to last myomeres to origin of pectoral fm a. with distinct continuous or nearly contin- a. 12-16% SL C. ardens uous lines of melanophores along (paral- C. discobolus lel to) each side of dorsal midline (Fig. b. 17-19% SL C. ardens 57) 69 b. with distinctly shorter or discontinuous 54 (44). Pectoral fm length lines of melanophores along one or both a. -.•"9% SL 55 sides of dorsal midline (Figs. 15, 43, b. 10-12% SL C. platyrhynchus 85) 47 c. without distinct lines of melanophores 55 (54). Yolk length along either side of dorsal midline (Figs. a. 15.40% SL C. platyrhynchus 44,71) ...... 48 b. 41% SL or more ...... 108

47 (46). Dorsal midline from shortly behind 56 (50). Length from anterior margin of snout head to near last myomeres to posterior margin of eye

42 a. 6-8% 57 70 (69). Pectoral fin length b. 9% SL C. ardens a. s9% SL 71 b. 10-12% SL X. texanus 57 (56). Pectoral fin length a. :59% SL 58 71 (70). Yolk length b. 10-12% SL X. texanus a. S40% SL X. texanus b. 2:41% SL 72 58 (57). Yolk length a. s40% SL X. texanus 72 (71). Length from anterior margin of snout b. .41% SL 59 to origin of pectoral fin a. 12-16% SL C. latipinnis 59 (58). Number of myomeres to posterior X. teranus margin of vent b. 17-19% SL X. texanus a. 35-36 C ardens b. 37-39 C ardens 73 (33,41). Length from anterior margin of X. texanus snout to posterior margin of eye c. 40-41 X. texanus a. 6-8% 74 b. 9% SL 120 60 (30). Length from anterior margin of snout to posterior margin of eye 74 (73). Number of myomeres to posterior a. 6-8% 61 margin of vent b. 9% SL C commersoni a. 35-36 C. ardens b. 37-39 75 61 (60). Yolk length c. 40-41 C. latipinnis a. 21-40% SL C commersoni C. discobolus b. 2:41% SL 62 75 (74). Length from anterior margin of snout 62 (61). Pectoral fin length to origin of pectoral fin a. s9% SL 63 a. 12-16% SL C ardens b. 10-12% SL C commersoni C. discobolus C. latipinnis 63 (62). Length from anterior margin of snout b. 17-19% SL C ardens to origin of pectoral fin a. 12-16% SL 91 76 (42). Pectoral fin length b. 17-19% SL C commersoni a. 59% SL 77 b. 10-12% SL C platyrhynchus 64 (42,43). Pectoral fin length 65 a. :59% SL 77 (76). b. 1042% SL platyrhynchus Yolk length C a. S40% SL C. platyrhynchus b. .111% SL 78 65 (64). Length from anterior margin of snout to origin of pectoral fin a. 12-14% SL C. discobolus 78 (77). Number of myomeres to posterior b. 15-16% SL 66 margin of vent c. 17-19% SL platyrhynchus a. 34-36 108 C. b. 37-39 79 c. 40-41 discobolus 66 (65). Number of myomeres to posterior C. margin of vent a. 34-36 C platyrhynchus 79 (78). Length from anterior margin of snout b. 37-39 67 to origin of pectoral fm c. 40-41 C. discobolus a. 12-14% SL C. discobolus C. ardens 67 (66). Length from anterior margin of snout b. 15-16% SL 80 to posterior margin of eye c. 17-19% SL 109 a. 6-8% 68 b. 9-10% SL C platyrhynchus 80 (79). Length from anterior margin of snout a. 6_8%to posterior margin of eye 68(67). Yolk length C. platyrhynchus a. s40% SL C platyrhynchus C. ardens b. 2._41% SL C platyrhynchus C. discobolus C. discobolus b. 9% SL C platyrhynchus C. ardens 69 (46). Length from anterior margin of snout c. 10% SL C. platyrhynchus to posterior margin of eye a. 6-8% 70 81 (14). Length from anterior margin of snout b. 9% SL C. latipinnis to posterior margin of eye

43 a. 6-8% 82 c. 40-41 C commersoni b. 9% SL C. ardens C. discobolus

82 (81). Pectoral fm length 93 (6,38,87). Yolk length a. -59% SL 83 a. ..0% SL C. plcayrhynchus b. 10-12% SL X. texanus b. -21% SL 94

83 (82). Yolk length 94 (88,93). Length from anterior margin of a. up-40% SL X. texanus snout to posterior margin of eye b. ?.1.41% SL 84 a. 6-9% SL 95 b. 10% SL C platyrhynchus 84 (83). Number of myomeres to posterior margin of vent 95 (89,94). Length from anterior margin of a. 35-36 C. ardens snout to origin of pectoral fm b. 37-39 85 a. 12-14% SL C commersoni c. 40-41 86 b. 15-19% SL 96

85 (84). Length from anterior margin of snout 96 (90,95). Number of myomeres to posterior to origin of pectoral fin margin of vent a. 12-16% SL C ardens a. 34-39 C. commersoni C. discobolus C. platyrhynchus X. texanus b. 40-41 C commersoni b. 17-19% SL X. texanus C. ardens 97 (41). Pectoral fm length 86 (84). Length from anterior margin of snout a. 59% SL 98 to origin of pectoral fin b. 10-12% SL C. platyrhynchus a. 12-16% SL C. discobolus X. texanus 98 (97). Yolk length b. 17-19% SL ... X. texanus a. 540% SL C. platyrhynchus b. .41% SL 99 87 (37). Pectoral fin length a. 59% SL 88 99 (98). Length from anterior margin of snout b. 10-12% SL 93 to origin of pectoral fin a. 12-14% SL 113 88 (87). Yolk length b. 15-16% SL 100 a. 520% SL C. platyrhynchus c. 17-19% SL C platyrhynchus b. 21-40% SL 94 c. ?Al% SL 89 100 (99). Number of myomeres to posterior margin of vent 89 (88). Length from anterior margin of snout a. 34-36 C. platyrhynchus to posterior margin of eye b. 37-39 101 a. 6-8% SL 90 c. 40-41 113 b. 9% SL 95 c. 10% SL C platyrhynchus 101 (100). Length from anterior margin of snout a. 6_8%to posterior margin of eye 90 (89). Length from anterior margin of snout C. platyrhynchus to origin of pectoral fm C. discobolus a. 12-14% SL 91 C. latzpinnis b. 15-16% SL 92 b. 9% SL C plcayrhynchus c. 17-19% SL 96 C. latipinnis c. 10% SL C. platyrhynchus 91 (63,90). Number of myomeres to posterior margin of vent 102 (47). Length from anterior margin of snout a. 34-36 C commersoni to posterior margin of eye b. 37-41 C. commersoni a. 6-8% 103 C. discobolus b. 9% SL C. lattpinnis

92 (90). Number of myomeres to posterior 103 (102). Pectoral fin length margin of vent a. .59% SL 104 a. 34-36 C. platyrhynchus b. 10-12% SL X. tetanus C. commersoni b. 37-39 C. platyrhynchus 104 (103). Yolk length C. commersoni a. 540% SL X. texanus C. discobolus b. SL 119

44 105 (41). Pectoral fin length a. 540% SL X. tetanus a. 59% SL 106 b. 1-41% SL 116 b. 10-12% SL C. platyrhynchus 116 (115). Length from anterior margin of snout 106 (105). Yolk length to posterior margin of eye a. 540% SL C platyrhynchus a. 6-8% 117 b. a-41% SL 107 b. 9% SL 120

107 (106). Number of myomeres to posterior 117 (116). Number of myomeres to posterior margin of vent margin of vent a. 34-36 108 a. 35-36 C. ardens b. 37-39 110 b. 37-39 118 c. 40-41 113 c. 40-41 119

108 (55,78,107). Length from anterior margin of 118 (117). Length from anterior margin of snout snout to origin of pectoral fin to origin of pectoral fin a. 12-14% SL C. ardens a. 12-16% SL C. discobolus b. 15-19% SL 109 C. latipinnis X. texanus 109 (79,108). Length from anterior margin of C. ardens snout to posterior margin of eye b. 17-19% SL C. ardens a. 6-9% SL C ardens X. tetanus C. platyrhynchus b. 10% SL C. platyrhynchus 119 (104,117). Length from anterior margin of snout to origin of pectoral fin 110 (107). Length from anterior margin of snout a. 12-16% SL X. texanus to posterior margin of eye C. discobolus a. 6-8% SL 111 C. latipinnis b. 9% SL 112 b. 17-19% SL X. texanus c. 10% SL C. platyrhynchus 120 (17,18,73,116). Number of myomeres to 111 (110). Length from anterior margin of snout posterior margin of vent to origin of pectoral fin a. 35-36 C. ardens a. 12-14% SL C ardens b. 37-39 121 C. discobolus c. 40-41 C. latipinnis C. latipinnis b. 15-16% SL C. latipinnis 121 (120). Length from anterior margin of snout C. ardens to origin of pectoral fm C. discobolus a. 12-16% SL C. ardens C. platyrhynchus C. latipinnis c. 17-19% SL C. platyrhynchus b. 17-19% SL C. ardens C. ardens 122 (10). Pectoral fm length 112 (110). Length from anterior margin of snout a. 59% SL 123 to origin of pectoral fin b. 10-12% SL 129 a. 12-14% SL C. ardens C. latipinnis 123 (122). Yolk length b. 15-16% SL C. plaiyrhynchus a. .JZI% SL X. term:us C. ardens b. 21-40% SL 130 C. latipinnis c. SL 124 c. 17-19% SL C. ardens C. platyrhynchus 124 (123). Length from anterior margin of snout to posterior margin of eye 113 (33,99,100,107). Length from anterior a. 6-8% SL 125 margin of snout to posterior margin b. 9% SL 127 of eye a. 6-8% SL C. discobolus 125 (124). Number of myomeres to posterior C. latipinnis margin of vent b. 9% SL C. latipinnis a. 34-36 C. ardens C. commersoni 114 (13,47). Pectoral fm length b. 37-39 126 a. 59% SL as c. 40-41 137 b. 10-12% SL ...... X. texanus 126 (125). Length from anterior margin of snout 115 (114). Yolk length to origin of pectoral fin

45 a. 12-16% SL C. latipinnis C. latipinnis C. discobolus X. texanus X. texanus b. 15-16% SL C. latipinnis C. commersoni X. texanus C. ardens C. ardens b. 17-19% SL C. commersoni C. commersoni C. ardens C. discobolus X. teranus C. platyrhynchus c. 17-19% SL C. platyrhynchus 127 (124). Number of myomeres to posterior C. commersoni margin of vent X. texanus a. 34-36 C commersoni C. ardens C. ardens b. 37-39 128 137 (125,135). Length from anterior margin of c. 40-41 141 snout to origin of pectoral fin a. 12-16% SL X. texanus 128 (127). Length from anterior margin of snout C. comrnersoni to origin of pectoral fin C. discobolus a. 12-16% SL C. latipinnis C. latipinnis C. ardens b. 17 to 19% SL X. texanus C. commersoni C. commersoni b. 17-19% SL C commersoni C. ardens 138 (134). Number of myomeres to posterior margin of vent 129 (3,11,122). Yolk length a. 34-36 139 b. 37-39 140 a. . 20% SL X. texanus b. 221% SL 130 c. 40-41 141 139 (1.38). 130 (123,129). Length from anterior margin of Length from anterior margin of snout snout to posterior margin of eye to origin of pectoral fin a. 6-8% SL 131 a. 12-14% SL C. ardens b. 9% SL C commersoni C. commersoni b. 15-19% SL C. commersoni 131 (130). myomeres C. platyrhynchus Number of to posterior C. ardens margin of vent a. 34-36 C commersoni b. 37-41 C commersoni 140 (138). Length from anterior margin of snout X. texanus to origin of pectoral fin a. 12-14% SL C. commersoni C. ardens 132 (10). Pectoral fin length C. latipinnis a. :59% SL 133 b. 15-16% SL C. platyrhynchus 142 b. 10-12% SL C. ardens C. commersoni 133 (132). Yolk length C. latipinnis a. .20% SL 146 c. 17-19% SL C. commersoni b. 21-40% SL 149 C. platyrhynchus c. SL 134 C. ardens

134 (133). Length from anterior margin of snout 141 (127,138). Length from anterior margin of to posterior margin of eye snout to origin of pectoral fin a. 6-8% SL 135 a. 12-16% SL C. latipinnis b. 9% SL 138 C. commersoni c. 10% SL C. platyrhynchus b. 17-19% SL C. commersoni

135 (134). Number of myomeres to posterior 142 (5,11,132). Length from anterior margin of margin of vent snout to posterior margin of eye a. 34-36 ...... 148 a. 6-8% SL 143 b. 37-39 ...... 136 b. 9% SL 153 c. 40-41 ...... 137 c. 10% SL C platyrhynchus

136 (135). Length from anterior margin of snout 143 (142). Number of myomeres to posterior to origin of pectoral fm margin of vent a. 12-14% SL C commersoni a. 34-36 154 C. ardens b. 37-39 145 C. discobolus c. 40-41 144

46 144 (143). Yolk length a. 34-36 155 a. . -20% SL X. texanus b. 37-39 152 b. L-21% SL X. texanus c. 40-41 X. texanus C. commersoni C. commersoni

145 (143). Yolk length 151 (149). Number of myomeres to posterior a. 20% SL 148 margin of vent b. ..>_-21% SL 152 a. 34-39 155 b. 40-41 C. commersoni 146 (133). Length from anterior margin of snout to posterior margin of eye 152 (145,150). Length from anterior margin of a. 6-8% SL 147 snout to origin of pectoral fin b. 9-10% SL C. platyrhynchus a. 12-14% SL X. texanus 147 (146). Number of myomeres to posterior C. commersoni margin of vent b. 15-19% SL X. tetanus a. 34-36 C platyrhynchus C. commersoni b. 37-39 148 C. platyrhynchus c. 40-41 X. texanus 153 (142). Number of myomeres to posterior 148 (135,145,147). Length from anterior margin margin of vent of snout to origin of pectoral fin a. 34-39 154 a. 12-14% SL X. texanus b. 40-41 C commersoni b. 15-19% SL X. texanus C. platyrhynchus 154 (143,153). Yolk length 149 (133). Length from anterior margin of snout a. s20% SL C platyrhynchus to posterior margin of eye b. .21% SL 155 a. 6-8% SL 150 b. 9% SL 151 155 (150,151,154). Length from anterior margin c. 10% SL C. platyrhynchus of snout to origin of pectoral fin a. 12-14% SL C commersoni 150 (149). Number of myomeres to posterior b. 15-19% SL C cornmersoni margin of vent C. platyrhynchus

Flexion Mesolarvae -- at least one fin ray a. with .21 melanophores (Fig. 30) present in caudal fin but not the full adult C commersoni complement of 18 principal rays (definition b. with 1-20 melanophores (Fig. 58) abbreviated for species of concern; Fig. 16). C. latipinnis 7 (3). Ventral midline from shortly behind heart 1. Standard (notochord) length (SL; Fig. 4) region to near vent a. 10 mm 8 a. with -21 melanophores (if in a contin- b. 11 mm 11 uous or nearly continuous line and mid- c. 12 mm 23 line pigment extends into branchial d. 13 mm 19 region anterior to heart, probably C. e. 14 mm 3 commersoni; Fig.31) (Figs. 30, 72) . . . . 45 f. 15 mm 2 b. with melanophores or without pigment (Fig. 16) C. ardens 2 (1). Yolk a. present ...... C. latipinnis 8 (1). Yolk b. absent ...... C commersoni a. present ...... 9 b. absent ...... 10 3 (1). Yolk a. present ...... 4 9 (8). Maximum depth of yolk b. absent ...... 7 SL C. discobolus b. SL 10 4 (3). Maximum depth of yolk a. -5% SL C. latipinnis 10 (8,9). Ventral midline from shortly behind b. ..-54% SL 5 heart region to near vent a. with .>_.21 melanophores in a continuous 5 (4). Length of yolk or nearly continuous line or narrow a. ?..-19% SL 6 band (Fig. 30) C. commersoni b. . 18% SL C commersoni b. with ..21 melanophores in a shorter or a distinctly discontinuous line (Fig. 44) . 26 6 (5). Ventral midline from shortly behind heart c. with 7-20 melanophores (Fig 17) region to near vent C. discobolus

d. with melanophores or without pig- more shorter segments, or a distinctly ment (Fig. 86) 16 discontinuous line (Figs. 45, 86) 51 b. with melanophores in one or more 11(1). Yolk short lines, a discontinuous, well-spaced line or (rarely) no distinct line of a. present ...... 12 b. absent ...... 15 melanophores X. texanus

12 (11). Maximum depth of yolk 19 ( 1). Yolk a. SL C. discobolus a. present 20 b. SL 13 b. absent 44

13 (12). Length of yolk 20 (19). Maximum depth of yolk a. 2:19% SL 14 a. L-5% SL 35 b. . 18% SL 15 b. SL 21

14 (13). Ventral midline from shortly behind 21(20). Length of yolk heart region to near vent a. SL 22 a. with 2:21 melanophores in a continuous b. - 18% SL 25 or nearly continuous line or narrow band (Fig. 30) C commersoni 22 (21). Ventral midline from shortly behind b. with ?.-21 melanophores in a shorter or heart region to near vent a distinctly discontinuous line (Fig. 44) . 26 a. with melanophores in a continuous c. with 7-20 melanophores (Fig. 17) or nearly continuous line or narrow C. discobolus band (Fig. 30) C. commersoni d. with 5.6 melanophores or without pig- b. with 2:21 melanophores in a shorter or ment (Fig. 86) 16 a distinctly discontinuous line (Fig. 44) . 26 c. with 1-20 melanophores (Figs. 16, 58) . . 27 15 (11,13). Ventral midline from shortly behind d. without pigment ...... 47 heart region to near vent 2: a. with 21 melanophores in a continuous 23 (1). Yolk or nearly continuous line or narrow band a. present ...... 24 (if midline pigment extends into bran- b. absent ...... 44 chial region anterior to heart, probably C. commersoni; Fig. 31) (Figs. 30, 72) . 45 b. with melanophores in a shorter or 24 (23). Maximum depth of yolk a distinctly discontinuous line (Fig. 44) a. 2:5% SL C. discobolus 46 b. -' 4% SL 25 c. with 7-20 melanophores (Fig. 17) C. discobolus 25 (21,24). Ventral midline from shortly behind d. with :56 melanophores or without pig- heart region to near vent ment (Fig. 86) 16 a. with melanophores in a continuous or nearly continuous line or narrow 16 (10,14,15). Dorsal body pigmentation band (Fig. 30) C. commersoni between head and last myomere b. with ?_.-21 melanophores in a shorter or a. scattered with no distinct lines of melan- a distinctly discontinuous line (Fig. 44) . 26 ophores on or lateral (and parallel) to c. with s20 melanophores or without dorsal midline (Fig. 44) . . . . C. discobolus pigment (Fig. 16) 47 b. including at least a partial distinct line of melanophores on or lateral (and paral- 26 (10,14,22,25). Dorsal body pigmentation lel) to dorsal midline (Fig. 86) 17 between head and last myomere a. scattered with no distinct lines of melan- 17 (16). Dorsal surface lateral to midline from ophores on or lateral (and parallel) to shortly behind head to about 2/3 dorsal midline (Fig. 44) . . . . C. discobolus distance to last myomeres b. including at least a partial distinct line of a. with distinct lines of melanophores along melanophores on or lateral (and paral- one or both sides of dorsal midline (Fig. lel) to dorsal midline (Fig. 30) 79 86) 18 b. without distinct lines of melanophores 27 (22). Dorsal body pigmentation between head along either side of dorsal midline (Fig. and last myomere 44) C. discobolus a. scattered with no distinct lines of melanophores on or lateral (and parallel) to 18 (17). Dorsal midline from shortly behind dorsal midline (Fig. 44) . . . . C. discobolus head to near last myomeres b. including at least a partial distinct line of a. with 2:25 melanophores in a distinct con- melanophores on or lateral (and paral- tinuous or nearly continuous line, one or lel) to dorsal midline (Figs. 16, 58) . . . . 28

48 28 (27). Dorsal surface lateral to midline from a. with melanophores (Fig. 44) shortly behind head to about 2/3 C. discobolus distance to last myomeres b. with 1-20 melanophores (Fig. 58) 36 a. with distinct lines of melanophores along c. without pigment ...... C. discobolus one or both sides of dorsal midline (Figs. 16, 58) 29 36 (35). Dorsal body pigmentation between head b. without distinct lines of melanophores and last myomere along either side of dorsal midline (Fig. a. scattered with no distinct lines of melan- 44) C. discobolus ophores on or lateral (and parallel) to dorsal midline (Fig. 44) . . . . C. discobolus 29 (28). Melanophores in lines lateral (and b. including at least a partial distinct line of parallel) to dorsal midline between melanophores on or lateral (and head and 2/3 distance to last parallel) to dorsal midline (Fig. 58) . . . 37 myomeres a. mostly in single file (Fig. 16) 30 37(36). Dorsal surface lateral to midline from b. mostly in obliquely oriented pairs or shortly behind head to about 2/3 groups resulting in a "herring bone" or distance to last myomeres "tractor tread" pattern (Fig. 58) a. with distinct lines of melanophores along C. latipinnis one or both sides of dorsal midline (Fig. 58) 38 30 (29). Dorsal midline from shortly behind b. without distinct lines of melanophores head to near last myomeres along either side of dorsal midline (Fig. a. with •._25 melanophores in a distinct 44) C. discobolus continuous or nearly continuous line (Fig. 43) C. discobolus 38(37). Melanophores in lines lateral (and b. with melanophores but in one or parallel) to dorsal midline between more shorter segments or a distinctly head and 2/3 distance to last discontinuous line (Fig. 45) 65 myomeres c. with :s24 melanophores in one or more a. mostly in single file (Fig. 43) 39 short lines, a discontinuous, well-spaced b. mostly in obliquely oriented pairs or line or (rarely) no distinct line of groups resulting in a "herring bone" or melanophores (Figs. 16, 59) 31 "tractor tread" pattern (Fig. 58) C. lafipinnis from shortly behind 31 (30). Ventral to ventro-lateral surfaces of gill 39 (38). Dorsal midline covers (opercula) head to near last myomeres a. unpigmented (Fig. 58) 32 a. with ?_25 melanophores in a distinct continuous or nearly continuous line b. pigmented (Fig. 17) C. ardens (Fig. 43) C. discobolus b. with melanophores but in one or 32 (31). Chin (anterior ventral surface of lower more shorter segments or a distinctly jaw) discontinuous line (Fig. 45) 40 unpigmented (Figs. 16, 58) 33 a. C. with melanophores in one or more ardens b. pigmented (Fig. 17) C. short lines, a discontinuous, well-spaced line or (rarely) no distinct line of 33 (32). Lateral surface of body above horizon- melanophores (Fig. 58) C. latipinnis tal myosepta (lateral midline) and below dorso-lateral surface (exclu- 40 (39). Chin (anterior ventral surface of lower sive of pigment associated with jaw) horizontal myosepta, air bladder, or a. unpigmented (Figs. 44, 58) 41 visceral peritoneum) b. pigmented (Fig. 30) C. discobolus a. unpigmented (Figs. 16, 58) 105 b. pigmented (at least 1 melanophore) 41 (40). Lateral surface of head posterior to (Fig. 17) 34 eyes a. unpigmented (Fig. 44) C. discobolus 34 (33). Lateral surface of body below horizon- b. pigmented (at least 1 melanophore) tal myosepta (lateral midline) (Fig. 58) 42 (exclusive of pigment associated with horizontal myosepta, air bladder, 42 (41). Lateral surface of body above horizon- visceral peritoneum, or gut) tal myosepta (lateral midline) and a. unpigmented (Figs. 16, 58) 105 below dorso-lateral surface (exclu- b. pigmented with at least 1 melanophore sive of melanophores associated (Fig. 17) C. ardens with horizontal myosepta, air bladder, or visceral peritoneum) 35 (20). Ventral midline from shortly behind a. unpigmented (Fig. 58) C. discobolus heart region to near vent C. latipinnis

49 b. pigmented with 1-5 melanophores (Fig. 49 (48). Dorsal surface lateral to midline from 44) 43 shortly behind head to about 2/3 c. pigmented with melanophores (Fig. distance to last myomeres 46) C. discobolus a. with distinct lines of melanophores along (parallel to) one or both sides of dorsal 43 (42). Lateral surface of body below midline (Figs. 16, 86) ...... 50 horizontal myosepta (lateral b. without distinct lines of melanophores midline) (exclusive of pigment along either side of dorsal midline (Fig. associated with horizontal myosepta, 44) C. discobolus air bladder, visceral peritoneum, or gut) 50(49). Dorsal midline from shortly behind a. unpigmented (Fig. 58) C. discobolus head to near last myomeres C. latipinnis a. with a-25 melanophores in a distinct b. pigmented with at least 1 melanophore continuous or nearly continuous line (Fig. 45) C. discobolus (Fig. 43) 51 b. with ?_.25 melanophores but in one or 44 (19,23). Ventral midline from shortly behind more shorter segments or a distinctly heart region to near vent discontinuous line (Fig. 45) 55 - a. with .21_ melanophores in a continuous c. with . 24 melanophores in one or more or nearly continuous line or narrow band short lines, a discontinuous, well-spaced (if midline pigment extends into bran- line or (rarely) no distinct line of chial region anterior to heart, probably melanophores (Figs. 16, 86) 53 C. commersoni; Fig. 31) (Figs. 30, 72) . . 45 b. with melanophores in a shorter or 51 (18,50). Dorsal surface of head pigmented a distinctly discontinuous line (Fig. 44) . 46 a. only over hindbrain (posterior to middle c. with 7-20 melanophores (Fig. 17) 47 of eyes; Fig. 86) X. texanus d. with ..45 melanophores or without pig- b. over both mid- and hindbrain (anterior ment (Figs. 16, 86) 48 and posterior to middle of eyes; Fig. 44) 52 45 (7,15,44). Dorsal body pigmentation between head and last myomere 52 (51). Ventral to ventro-lateral surfaces of gill a. scattered with no distinct lines of melan- covers (opercula) ophores on or lateral (and parallel) to a. unpigmented (Figs. 44, 86) 58 dorsal midline (Fig. 44) . . C. platyrhynchus b. pigmented (Figs. 17, 31) X. tetanus b. including at least a partial distinct line of melanophores on or lateral (and paral- 53 (50). Dorsal surface of head pigmented lel) to dorsal midline (Figs. 30, 72) . . . . 76 a. only over hindbrain (posterior to middle of eyes; Fig. 86) X. texanus b. over both mid- and hindbrain (anterior 46 (15,44). Dorsal body pigmentation between and posterior to middle of eyes; Fig. head and last myomere 16) 54 a. scattered with no distinct lines of melanophores on or lateral (and parallel) to 54 (53). Ventral to ventro-lateral surfaces of gill dorsal midline (Fig. 44) 72 covers (opercula) b. including at least a partial distinct line of a. unpigmented or pigmented but not in melanophores on or lateral (and paral- distinct oblique rows (Figs. 16, 86) . . . . 60 midline lel) to dorsal (Figs. 30, 45, 72) 80 b. pigmented in a distinct oblique row of 3 or more melanophores near or along 47 (22,25,44). Dorsal body pigmentation ventral margin of one or both preoper- between head and last myomere des (Figs. 17, 31) X. tetanus a. scattered with no distinct lines of melanophores on or lateral (and parallel) to 55 (50). Dorsal surface of head pigmented dorsal midline (Fig. 44) . . . . C. discobolus a. only over hindbrain (posterior to middle b. including at least a partial distinct line of of eyes; Fig. 86) X. tetanus melanophores on or lateral (and paral- b. over both mid- and hindbrain (anterior lel) to dorsal midline (Figs. 16,45) . . . . 62 and posterior to middle of eyes; Figs. 16,44) ...... 56 48(44). Dorsal body pigmentation between head and last myomere 56 (55). Ventral to ventro-lateral surfaces of gill a. scattered with no distinct lines of melan- covers (opercula) ophores on or lateral (and parallel) to a. unpigmented (Figs. 44, 86) 57 dorsal midline (Fig. 44) . . . . C. discobolus b. pigmented in a distinct oblique row of 3 b. including at least a partial distinct line of or more melanophores near or along melanophores on or lateral (and paral- ventral margin of 1 or both preopercles lel) to dorsal midline (Figs. 16, 45, 86) . 49 (Figs. 17, 31) X. tetanus

50 c. pigmented but not in distinct oblique c. with <4 melanophores in one or more rows (Figs. 16) 60 short lines, a discontinuous, well-spaced line or (rarely) no distinct line of 57 (56). Lateral surface of head posterior to melanophores (Fig. 16) C ardens eyes 64 (63). Ventral to ventro-lateral surfaces of gill a. unpigmented (Fig. 44) 58 covers (opercula) b. pigmented (at least 1 melanophore) a. unpigmented (Fig. 44) 70 (Figs. 16, 86) 59 b. pigmented (at least 1 melanophore; Fig. 16) C. ardens 58 (52,57). Lateral surface of body above horizontal myosepta (lateral midline) 65 (30). Ventral to ventro-lateral surfaces of gill and below dorso-lateral surface covers (opercula) (exclusive of melanophores asso- a. unpigmented (Figs. 44, 58) 66 ciated with horizontal myosepta, air b. pigmented (at least 1 melanophore; Fig. bladder, or visceral peritoneum) 16) C. ardens a. unpigmented (Fig. 86) 112 b. pigmented (at least 1 melanophore; Fig 66 (65). Chin (anterior ventral surface of lower 44) C. discobolus jaw) a. unpigmented (Figs. 16, 44, 58) 67 59 (57). Lateral surface of body above horizon- b. pigmented (at least 1 melanophore; Fig. tal myosepta (lateral midline) and 17) 70 below dorso-lateral surface (exclusive of melanophores associated with 67 (66). Lateral surface of head posterior to horizontal myosepta, air bladder, or eyes visceral peritoneum) a. unpigmented (Fig. 44) C. discobolus a. unpigmented (Figs. 16, 86) 113 b. pigmented (at least 1 melanophore; Figs. b. pigmented with 1-5 melanophores (Fig 16,58) ...... 68 44) 103 c. pigmented with 6 melanophores (Fig 68 (67). Lateral surface of body above horizon- 46) C. discobolus tal myosepta (lateral midline) and below dorso-lateral surface (exclu- 60 (54,56). Lateral surface of head posterior to sive of melanophores associated eyes with horizontal myosepta, air a. unpigmented (Fig. 44) X. texanus bladder, or visceral peritoneum) b. pigmented (at least 1 melanophore) a. unpigmented (Figs. 16, 58) 107 (Figs. 16, 86) 61 b. pigmented with 1-5 melanophores (Fig 44) 69 61(60). Lateral surface of body above horizon- c. pigmented with melanophores (Figs. tal myosepta (lateral midline) and 45, 46) C. discobolus below dorso-lateral surface (exclusive of melanophores associated with 69 (68). Lateral surface of body below horizon- horizontal myosepta, air bladder, or tal myosepta (lateral midline) visceral peritoneum) (exclusive of melanophores asso- a. unpigmented (Figs. 16, 86) 109 ciated with horizontal myosepta, air b. pigmented with 1-5 melanophores (Fig bladder, visceral peritoneum, or gut) 17) C. ardens a. unpigmented (Figs. 16, 44, 58) 107 b. pigmented (at least 1 melanophore) 62 (47). Dorsal surface lateral to midline from (Figs. 45, 46) 103 shortly behind head to about 2/3 distance to last myomeres 70 (64,66). Lateral surface of head posterior to a. with distinct lines of melanophores along eyes one or both sides of dorsal midline (Fig. a. unpigmented (Fig. 44) C. discobolus 16 63 b. pigmented (at least 1 melanophore; Fig. b. without distinct lines of melanophores 16) 71 along either side of dorsal midline (Fig. 44) C. discobolus 71(70). Lateral surface of body above horizontal myosepta (lateral midline) and 63 (62). Dorsal midline from shortly behind below dorso-lateral surface (exclu- head to near last myomeres sive of melanophores associated a. with melanophores in a distinct with horizontal myosepta, air continuous or nearly continuous line bladder, or visceral peritoneum) (Fig. 43) C. discobolus a. unpigmented or pigmented with b. with melanophores but in one or melanophores (Figs. 16, 44) 103 more shorter segments or a distinctly b. pigmented with melanophores (Figs discontinuous line (Fig. 45) 64 45, 46) C. discobolus

51 72 (46). Ventral to ventro-lateral surfaces of gill b. without distinct lines of melanophores covers (opercula) along either side of dorsal midline (Fig. a. unpigmented (Figs. 44, 72) 73 44) 82 b. pigmented (Fig. 73) C platyrhynchus 80 (46). Dorsal surface lateral to midline from 73 (72). Ventral surface of heart region shortly behind head to about 2/3 a. unpigmented (Fig. 45) C. discobolus distance to last myomeres b. pigmented (Figs. 44, 72) 74 a. with distinct continuous or nearly continuous lines of melanophores along 74 (73). Lateral surface of head posterior to (parallel to) each side of dorsal midline eyes (Fig. 30) 81 a. unpigmented (Fig. 44) C. discobolus b. with distinctly shorter or discontinuous b. pigmented (at least 1 melanophore; Fig. lines of melanophores along one or both 72) 75 sides of dorsal midline (Fig. 43) 83 c. without distinct lines of melanophores 75 (74). Lateral surface of body above horizon- along either side of dorsal midline (Fig. tal myosepta (lateral midline) and 44) 84 below dorso-lateral surface (exclusive of pigment associated with 81 (79,80). Melanophores in lines lateral (and horizontal myosepta, air bladder, or parallel) to dorsal midline between visceral peritoneum) head and 2/3 distance to last a. unpigmented (Fig. 72) 99 myomeres b. pigmented (at least 1 melanophore; Fig. a. mostly in single file (Fig. 43) 82 44) C. discobolus b. mostly in obliquely oriented pairs or groups resulting in a "herring bone" or 76 (45). Dorsal surface lateral to midline from "tractor tread" pattern (Fig. 30) shortly behind head to about 2/3 C. commersoni distance to last myomeres a. with distinct continuous or nearly 82 (79,81). Dorsal midline from shortly behind continuous lines of melanophores along head to near last myomeres (parallel to) each side of dorsal midline a. with z:25 melanophores in a distinct con- (Fig. 30) C commersoni tinuous or nearly continuous line, one or b. with distinctly shorter or discontinuous more shorter segments or a distinctly lines of melanophores along one or both discontinuous line (Figs. 30, 45) 90 sides of dorsal midline (Fig. 43) 77 b. with melanophores in one or more c. without distinct lines of melanophores short lines, a discontinuous, well-spaced along either side of dorsal midline (Fig. line or (rarely) no distinct line of 44) 78 melanophores (Fig. 16) . . . C. commersoni

77 (76). Melanophores in lines lateral (and 83 (80). Melanophores in lines lateral (and parallel) to dorsal midline between parallel) to dorsal midline between head and 2/3 distance to last head and 2/3 distance to last myomeres myomeres a. mostly in single file (Fig. 43) 78 a. mostly in single file (Fig. 43) ...... 84 b. mostly in obliquely oriented pairs or b. mostly in obliquely oriented pairs or groups resulting in a "herring bone" or groups resulting in a "herring bone" or "tractor tread" pattern (Fig. 30) "tractor tread" pattern (Fig. 30) C commersoni C commersoni

78 (76,77). Dorsal midline from shortly behind 84 (80,83). Dorsal midline from shortly behind head to near last myomeres head to near last myomeres a. with melanophores in a distinct con- a. with .25 melanophores in a distinct continuous or nearly continuous line, one or tinuous or nearly continuous line, one or more shorter segments, or a distinctly more shorter segments or a distinctly discontinuous line (Figs. 30, 45) 89 discontinuous line (Figs. 30, 45) ...... 85 b. with melanophores in one or more b. with melanophores in one or more short lines, a discontinuous, well-spaced short lines, a discontinuous, well-spaced line or (rarely) no distinct line of line or (rarely) no distinct line of melanophores (Fig. 16) . . . C. commersoni melanophores (Fig. 16) . . . C. commersoni

79 (26). Dorsal surface lateral to midline from 85 (84). Ventral to ventro-lateral surfaces of gill shortly behind head to about 2/3 covers (opercida) distance to last myomeres a. unpigmented (Figs. 44, 72) 86 a. with distinct lines of melanophores along b. pigmented (Fig. 16) 89 one or both sides of dorsal midline (Fig. 30) 81 86 (85). Ventral surface of heart region

a. unpigmented (Fig. 45) C. discobolus a. up to 80% SL C. commersoni b. pigmented (Figs. 30, 44, 72) 87 C. discobolus b. 81% SL or more C commersoni 87 (86). Lateral surface of head posterior to 96 (89). Longitudinal eye diameter eyes a. unpigmented (Fig. 44) C. discobolus a. up to 29% of head length . • C. commersoni b. pigmented (at least 1 melanophore; Figs. b. 30% of head length or more ...... 97 30,72) ...... 88 97 (96). Length from anterior margin of snout to posterior margin of vent 88 (87). Lateral surface of body above horizon- a. up to 80% SL ...... 98 tal myosepta (lateral midline) and or more C. commersoni below dorso-lateral surface (exclu- b. 81% SL sive of pigment associated with myomeres to posterior horizontal myosepta, air bladder, or 98 (97). Number of visceral peritoneum) margin of vent platyrhynclzus a. unpigmented (Fig. 72) 100 a. up to 38 C. commersoni b. pigmented with 1-5 melanophores (Figs C. cornmersoni 30,44) ...... 94 b. 39 or more ...... C. c. pigmented with melanophores (Figs. 45, 46) C. discobolus 99 (75). Number of myomeres to posterior margin of vent a. up to 38 C. discobolus 89 (78,85). Lateral surface of body above hori- C. platyrhynchus zontal myosepta (lateral midline b. 39 or more ...... C. discobolus below dorso-lateral surface (exclusive of pigment associated with 100 (88). Longitudinal eye diameter horizontal myosepta, air bladder, or a. up to 29% of head length . . C. commersoni visceral peritoneum) b. 30% of head length or more ...... 101 a. unpigmented (Fig. 72) 96 b. pigmented with 1-5 melanophores (Fig. 101 (100). Length from anterior margin of snout 30) C. commersoni to posterior margin of vent a. up to 80% SL 102 90 (82). Ventral to ventro-lateral surfaces of gill b. 81% SL or more C commersoni covers (opercula) a. unpigmented (Fig. 44) 91 102 (101). Number of myomeres to posterior b. pigmented (Fig. 30) C commersoni margin of vent a. up to 38 C. discobolus 91 (90). Ventral surface of heart region C. commersoni a. unpigmented (Fig. 45) C. discobolus C. platyrhynchus b. pigmented (Figs. 30, 44) 92 b. 39 or more ...... C. commersoni C. discobolus 92 (91). Lateral surface of head posterior to 103 (59,69,71). Longitudinal eye diameter eyes a. 30 to 32% of head length . .. C. discobolus a. unpigmented (Fig. 44) C. discobolus b. 33% of head length or more ...... 104 b. pigmented (at least 1 melanophore; Fig. 30) 93 104 (103). Number of myomeres to posterior margin of vent a. up to 38 C. ardens 93 (92). Lateral surface of body above horizon- discobolus tal myosepta (lateral midline) and C. below dorso-lateral surface (exclu- b. 39 or more ...... C. discobolus sive of pigment associated with horizontal myosepta, air bladder, or 105 (33,34). Longitudinal eye diameter visceral peritoneum) a. 30 to 32% of head length ... . C. latipinnis b. 33% of head length or more ...... 106 a. unpigmented or pigmented with 1-5 melanophores (Figs. 30, 44) 94 106 (105). Number of myomeres to posterior b. pigmented with melanophores (Figs. margin of vent 45, 46) C. discobolus a. up to 38 C. ardens C. latipinnis 94 (88,93). Longitudinal eye diameter b. 39 or more ...... C. latipinnis a. up to 29% of head length .. C. commersoni b. 30% of head length or more ...... 95 107 (68,69). Longitudinal eye diameter a. 30 to 32% of head length ... . C. latipinnis 95 (94). Length from anterior margin of snout C. discobolus to posterior margin of vent b. 33% of head length or more ...... 108

53 108 (107). Number of myomeres to posterior 113 (59). Longitudinal eye diameter margin of vent a. up to 29% of head length ...... X. teranus a. up to 38 C ardens b. 30 to 32% of head length ...... 114 C. discobolus c. 33% of head length or more ...... 115 C. latipinnis b. 39 or more ...... C. discobolus 114 (112,113). Length from anterior margin of 109 (61). Longitudinal eye diameter C. latipinnis snout to posterior margin of vent a. up to 32% of head length ...... X. texanus a. up to 76% SL C. discobolus b. 33% of head length or more ...... 110 b. 77 to 80% SL C. discobolus X. texanus 110 (109). Number of myomeres to posterior c. 81% SL or more ...... X. texanus margin of vent a. up to 38 111 115 (113). Length from anterior margin of snout b. 39 or more ...... X. texanus to posterior margin of vent a. up to 76% SL C. discobolus C. ardens 111 (110). Length from anterior margin of snout b. 77 to 80% SL 116 to posterior margin of vent c. 81% SL or more ...... X. texanus a. up to 76% SL C ardens b. 77 to 80% SL C. ardens 116 (115). Number of myomeres to posterior X. texanus margin of vent c. 81% SL or more ...... X. tetanus a. up to 38 C. ardens C discobolus 112 (58). Longitudinal eye diameter X. texanus a. up to 29% of head length ...... X. texanus b. 39 or more ...... C. discobolus b. 30% of head length or more ...... 114 X. texanus

Postflexion Mesolarvae -- adult complement of d. 1-6 melanophores or without pigment principal caudal fin rays present but adult (Fig. 87) 7 complement of principal dorsal or anal fin rays lacking (Figs. 3,17; definition abbre- 3 (2B). Dorsal surface lateral to midline from viated for species of concern). Separate shortly behind head to about 2/3 distance to last myomeres with skeletal character key at end for confirma- a. distinct continuous or nearly continuous tion of identity or further diagnosis of lines of melanophores along (parallel to) specimens cleared (and preferably stained) each side of dorsal midline (Figs. 30, for bone. 31) C. commersoni b. distinctly shorter or discontinuous lines 1. Standard length (SL; Fig. 4) of melanophores along one or both sides a. 11 mm 2A of dorsal midline (Figs. 72, 73) 4 b. 12 mm 2B c. no distinct lines of melanophores along c. 13 mm 10 either side of dorsal midline (Figs. 44, d. 14 mm 27 45) 5 e. 15 mm 43 f. 16 mm ao 4 (3). Melanophores in lines lateral (and paral- g. 17 mm 101 lel) to dorsal midline between head h. 18-21 mm C. latipinnis and 2/3 distance to last myomeres mostly in 2A (1). Ventral midline from shortly behind a. single file (Fig. 31) 5 heart region to near vent with b. obliquely oriented pairs or groups a. a.7 melanophores (Fig. 17) . . C. discobolus resulting in a "herring bone" or "tractor b. 1-6 melanophores or without pigment tread" pattern (Figs. 30, 59) C. commersoni (Fig. 87) 7 5 (3,4). Pigmentation of peritoneum 2B (1). Ventral midline from shortly behind a. absent on lateral and ventro-lateral heart region to near vent with surfaces (Figs. 30, 44) 6 a. .?..21 melanophores in a continuous or b. at least sparse or patchy on lateral nearly continuous line or narrow band surfaces (Fig. 45) C. discobolus (Fig. 31) C commersoni b. melanophores in a shorter or a 6 (5). Principal dorsal fin rays distinctly discontinuous line (Fig. 45) . . 3 a. absent ...... 218 c. 7-20 melanophores (Fig. 17) . C. discobolus b. present (at least one) ...... 116

54 7 (2A,2B). Dorsal surface lateral to midline 14 (13). Principal dorsal fin rays from shortly behind head to about a. absent ...... 225 2/3 distance to last myomeres with b. present (at least one) ...... 119 a. distinct continuous or nearly continuous lines of melanophores along (parallel 15 (10). Dorsal surface lateral to midline from to) each side of dorsal midline (Fig. shortly behind head to about 2/3 17) X. texanus distance to last myomeres with b. distinctly shorter or discontinuous lines a. distinct continuous or nearly continuous of melanophores along one or both sides lines of melanophores along (parallel to) of dorsal midline or with no distinct each side of dorsal midline (Figs. 30, lines of melanophores along either side 31) C. commersoni of dorsal midline (Figs. 45, 87) 8 b. distinctly shorter or discontinuous lines of melanophores along one or both sides 8 (7). Pigmentation of peritoneum of dorsal midline (Figs. 72, 73) 16 a. absent on lateral and ventro-lateral c. no distinct lines of melanophores along surfaces (Figs. 44, 87) 9 either side of dorsal midline (Figs. 44, b. at least sparse or patchy on lateral 45) 17 surfaces (Fig. 45) C. discobolus 16 (15). Melanophores in lines lateral (and 9 (8). Principal dorsal fin rays parallel) to dorsal midline between a. absent ...... 288 head and 2/3 distance to last myo- b. present (at least one) ...... C. discobolus meres mostly in a. single file (Figs. 31, 43, 72, 73) ...... 17 10 (1). Ventral midline from shortly behind b. obliquely oriented pairs or groups heart region to near vent with resulting in a "herring bone" or "tractor a. melanophores in a continuous or tread" pattern (Figs. 30, 59) C. commersoni nearly continuous line or narrow band (if midline pigment extends into 17 (15,16). Pigmentation of peritoneum branchial region anterior to heart, most a. absent on lateral and ventro-lateral probably C. commersoni; Figs. 31, 73) . . 11 surfaces (Figs. 30, 44, 72) 18 b. -21 melanophores in a shorter or a b. at least sparse or patchy on lateral distinctly discontinuous line (Fig. 45)... 15 surfaces (Figs. 45, 73) 19 c. 7-20 melanophores (Fig. 17) 20 d. 1-6 melanophores or without pigment 18 (17). Principal dorsal fin rays 23 (Fig. 87) a. absent ...... 211 b. present (at least one) ...... 122 11(10). Dorsal surface lateral to midline from shortly behind head to about 2/3 19 (17). Principal dorsal fin rays distance to last myomeres with a. absent ...... 231 a. distinct continuous or nearly continuous b. present (at least one) ...... 125 lines of melanophores along (parallel to) each side of dorsal midline (Figs. 30, 31) C. commersoni 20 (10). Dorsal surface lateral to midline from b. distinctly shorter or discontinuous lines shortly behind head to about 2/3 of melanophores along one or both sides distance to last myomeres with of dorsal midline (Figs. 72, 73) 12 a. distinct continuous or nearly continuous c. no distinct lines of melanophores along lines of melanophores along (parallel to) either side of dorsal midline (Figs. 44, each side of dorsal midline (Fig. 17) 45) 13 C. ardens b. distinctly shorter or discontinuous lines 12 (11). Melanophores in lines lateral (and of melanophores along one or both sides parallel) to dorsal midline between of dorsal midline or with no distinct head and 2/3 distance to last myo- lines of melanophores along either side meres mostly in of dorsal midline (Figs. 16, 44, 45) . . 21 a. single file (Figs. 31, 72, 73) 13 b. obliquely oriented pairs or groups 21(20). Pigmentation of peritoneum resulting in a "herring bone" or "tractor a. absent on lateral and ventro-lateral tread" pattern (Figs. 30, 59) C. commersoni surfaces (Figs. 17, 44) 22 b. at least sparse or patchy on lateral 13 (11,12). Pigmentation of peritoneum surfaces (Fig. 45) C. discobolus a. absent on lateral and ventro-lateral surfaces (Figs. 30, 72) 14 22 (21). Principal dorsal fin rays b. at least sparse or patchy on lateral a. absent ...... 271 surfaces (Fig. 73) C. platyrhynchus b. present (at least one) ...... 146

55 23 (10). Dorsal surface lateral to midline from 30 (28,29). Pigmentation of peritoneum shortly behind head to about 2/3 a. absent on lateral and ventro-lateral sur- distance to last myomeres with faces or present on lateral surfaces only a. distinct continuous or nearly continuous (Figs. 30, 31, 72) 107 lines of melanophores along (parallel to) b. at least sparse or patchy on lateral and each side of dorsal midline (Fig. 17) . . 24 ventro-lateral surfaces (Figs. 73, 74) b. distinctly shorter or discontinuous lines C. platyrhynchus of melanophores along one or both sides of dorsal midline or with no distinct 31(27). Dorsal surface lateral to midline from lines of melanophores along either side shortly behind head to about 2/3 of dorsal midline (Figs. 45, 87) 25 distance to last myomeres with a. distinct continuous or nearly continuous 24 (23). Principal dorsal fm rays lines of melanophores along (parallel a. absent ...... 282 to) each side of dorsal midline (Figs. 30, b. present (at least one) C ardens 31) C commersoni b. distinctly shorter or discontinuous lines 25 (23). Pigmentation of peritoneum of melanophores along one or both sides a. absent on lateral and ventro-lateral sur- of dorsal midline (Figs. 72, 73) 32 faces (Figs. 17, 44, 87) 26 c. no distinct lines of melanophores along b. at least sparse or patchy on lateral sur- either side of dorsal midline (Figs. 44, faces (Fig. 45) C. discobolus 45) 33

26 (25). Principal dorsal fin rays 32 (31). Melanophores in lines lateral (and a. absent ...... 248 parallel) to dorsal midline between b. present (at least one) ...... 146 head and 2/3 distance to last myomeres mostly in a. single file (Figs. 31, 73) 33 27 (1). Ventral midline from shortly behind b. obliquely oriented pairs or groups heart region to near vent with resulting in a "herring bone" or "tractor a. melanophores in a continuous or tread" pattern (Figs. 30, 59) C. commersoni nearly continuous line or narrow band (if midline pigment extends into bran- 33 (31,32). Pigmentation of peritoneum chial region anterior to heart, most a. absent on lateral and ventro-lateral sur- probably C. commersoni) (Figs. 31, 73) . 28 faces or present on lateral surfaces only b. melanophores in a shorter or a dis- (Figs. 30, 31, 44, 72) 34 tinctly discontinuous line (Fig. 45) 31 b. at least sparse or patchy on lateral and c. 7-20 melanophores (Fig. 17) 35 ventro-lateral surfaces (Figs. 73, 74) d. 1-6 melanophores or without pigment C. plagyrhynchus (Fig. 87) 37 34 (33). Principal dorsal fin rays 28 (27). Dorsal surface lateral to midline from a. present (at least one) but full comple- shortly behind head to about 2/3 ment incomplete or ttnclearly formed . 122 distance to last myomeres with b. present with full (adult) complement a. distinct continuous or nearly continuous clearly formed and countable (principal lines of melanophores along (parallel to) fin rays are sufficiently formed when the each side of dorsal midline (Figs. 30, last principal ray, which consists of two 31) C commersoni separate ray elements or "branches" b. distinctly shorter or discontinuous lines based on the most posterior pterygio- of melanophores along one or both sides phore, is well defined) ...... 158 of dorsal midline (Figs. 72, 73) 29 c. no distinct lines of melanophores along 35 (27). Dorsal surface lateral to midline from either side of dorsal midline (Figs. 44, shortly behind head to about 2/3 45) 30 distance to last myomeres with a. distinct continuous or nearly continuous 29 (28). Melanophores in lines lateral (and lines of melanophores along (parallel to) parallel) to dorsal midline between each side of dorsal midline (Fig. 17) head and 2/3 distance to last myo- C. ardens meres mostly in b. distinctly shorter or discontinuous lines a. single file (Figs. 31, 73) 30 of melanophores along one or both sides b. obliquely oriented pairs or groups result- of dorsal midline or with no distinct ing in a "herring bone" or "tractor tread" lines of melanophores along either side pattern (Figs. 30, 59) C. commersoni of dorsal midline (Figs. 44, 45) 36

56 36 (35). Pigmentation of peritoneum 43 (1). Yolk a. absent on lateral and ventro-lateral a. present ...... C. latipinnis surfaces (Figs. 17, 44) 64 b. absent ...... 44 b. at least sparse or patchy on lateral surfaces (Fig. 45) C. discobolus 44(43). Ventral midline from shortly behind heart region to near vent with 37 (27). Dorsal surface lateral to midline from a. ?..21 melanophores in a continuous or shortly behind head to about 2/3 nearly continuous line or narrow band distance to last myomeres with (if midline pigment extends into bron- a. distinct continuous or nearly continuous chial region anterior to heart, most lines of melanophores along (parallel to) probably C. commersoni) (Figs. 31, 73) . 45 each side of dorsal midline (Fig. 17) .. 38 b. ?_21 melanophores in a shorter or a b. distinctly shorter or discontinuous lines distinctly discontinuous line (Fig. 45) . . 48 of melanophores along one or both sides c. 7-20 melanophores (Fig. 17) 54 of dorsal midline or with no distinct d. 1-6 melanophores (Fig. 59) 65 lines of melanophores along either side e. no pigment (Fig. 87) 75 of dorsal midline (Figs. 45, 87) 40 45 (44). Dorsal surface lateral to midline from 38 (37). Pigmentation of peritoneum shortly behind head to about 2/3 a. absent on lateral and ventro-lateral sur- distance to last myomeres with faces (Figs. 17, 87) 39 a. distinct continuous or nearly continuous b. at least sparse or patchy on lateral lines of melanophores along (parallel surfaces (Fig. 45) X. texanus to) each side of dorsal midline (Figs. 30, 31) C. commersoni 39 (38). Principal dorsal fm rays b. distinctly shorter or discontinuous lines a. absent ...... 282 of melanophores along one or both sides b. present (at least one) but full comple- of dorsal midline (Figs. 72, 73) 46 ment incomplete or unclearly formed . 130 c. no distinct lines of melanophores along c. present with full (adult) complement either side of dorsal midline (Figs. 44, clearly formed and countable (principal 45) 47 fin rays are sufficiently formed when the last principal ray, which consists of two 46 (45). Melanophores in lines lateral (and separate ray elements or "branches" parallel) to dorsal midline between based on the most posterior pterygio- head and 2/3 distance to last myo- phore, is well defined) C ardens meres mostly in a. single file (Figs. 31, 73) 47 40 (37). Pigmentation of peritoneum b. obliquely oriented pairs or groups result- a. absent on lateral and ventro-lateral ing in a "herring bone" or "tractor tread" surfaces (Figs. 17, 44, 87) 41 pattern (Figs. 30, 59) C commersoni b. at least sparse or patchy on lateral surfaces (Fig. 45) 42 47 (45,46). Pigmentation of peritoneum a. absent on lateral and ventro-lateral 41 (40). Principal dorsal fin rays surfaces or present on lateral surfaces a. absent ...... 282 only (Figs. 30, 31) C commersoni b. present (at least one) but full comple- b. at least sparse or patchy on lateral and ment incomplete or unclearly formed . 127 ventro-lateral surfaces (Fig 73) c. present with full (adult) complement C. platyrhynchus clearly formed and countable (principal fin rays are sufficiently formed when the 48(44). Gut (Fig. 5) last principal ray, which consists of two a. essentially straight or with bend less separate ray elements or "branches" than 90° (gut phase 1) or with at least based on the most posterior pterygio- 90° bend or partial s-shaped loop (gut phore, is well defined) ...... 171 phase 2) 49 b. with full loop (s-shape to near anterior 42 (40). Principal dorsal fin rays end of visceral cavity) but with neither a. absent ...... X. texanus limb of loop completely across ventral b. present (at least one) but full comple- midline (gut phase 3) C. discobolus ment incomplete or unclearly formed . 133 c. present with full (adult) complement 49 (48). Dorsal surface lateral to midline from clearly formed and countable (principal shortly behind head to about 2/3 fin rays are sufficiently formed when the distance to last myomeres with last principal ray, which consists of two a. distinct continuous or nearly continuous separate ray elements or "branches" lines of melanophores along (parallel based on the most posterior pterygio- to) each side of dorsal midline (Figs. 30, phore, is well defined) ...... C. discobolus 31) C. commersoni

57 b. distinctly shorter or discontinuous lines c. no distinct lines of melanophores along of melanophores along one or both sides either side of dorsal midline (Figs. 44, of dorsal midline (Figs. 72, 73) 50 45) 60 c. no distinct lines of melanophores along either side of dorsal midline (Figs. 44, 56 (55). Melanophores in lines lateral (and 45) 51 parallel) to dorsal midline between head and 2/3 distance to last myo- 50 (49). Melanophores in lines lateral (and meres mostly in parallel) to dorsal midline between a. single file (Fig. 17) 57 head and 2/3 distance to last myo- b. obliquely oriented pairs or groups meres mostly in resulting in a "herring bone" or "tractor a. single file (Figs. 31, 73) 51 tread" pattern (Fig. 59) C. latipinnis b. obliquely oriented pairs or groups resulting in a "herring bone" or "tractor 57 (56). Pigmentation of peritoneum tread" pattern (Figs. 30, 59) C. commersoni a. absent on lateral and ventro-lateral surfaces (Figs. 17, 59) 58 51 (49,50). Pigmentation of peritoneum b. at least sparse or patchy on lateral sur- a. absent on lateral and ventro-lateral faces only (Fig. 18) C. ardens surfaces or present on lateral surfaces only (Figs. 30, 31, 44) 52 58 (57). Principal dorsal fin rays b. at least sparse or patchy on lateral and a. absent ...... 278 ventro-lateral surfaces (Figs. 45, 73) . . 53 b. present (at least one) but full complement incomplete or unclearly formed . 150 c. present with full (adult) complement 52 (51). Principal dorsal fin rays clearly formed and countable (principal a. present (at least one) but full comple- fm rays are sufficiently formed when the ment incomplete or unclearly formed . 116 last principal ray, which consists of two b. present with full (adult) complement separate ray elements or "branches" clearly formed and countable (principal based on the most posterior pterygio- fin rays are sufficiently formed when the phore, last principal ray, which consists of two is well defined) ...... C. ardens separate ray elements or "branches" 59 (55). Melanophores based on the most posterior pterygio- in lines lateral (and parallel) to dorsal midline between phore, is well defined) ...... 161 head and 2/3 distance to last myomeres mostly in 53 (51). Principal dorsal fin rays a. single file (Fig. 17) 60 a. present (at least one) but full comple- b. obliquely oriented pairs or groups ment incomplete or unclearly formed . 125 resulting in a "herring bone" or "tractor b. present with full (adult) complement tread" pattern (Fig. 59) C. latipinnis clearly formed and countable (principal fin rays are sufficiently formed when the 60 (55,59). Pigmentation of peritoneum last principal ray, which consists of two a. absent on lateral and ventro-lateral sur- separate ray elements or "branches" faces (Figs. 17, 44, 59) 61 based on the most posterior pterygio- b. at least sparse or patchy on lateral sur- phore, is well defined) ...... 167 faces only (Fig. 18) 64 c. at least sparse or patchy on lateral and 54 (44). Gut (Fig. 5) ventro-lateral surfaces (Fig. 45) a. essentially straight or with bend less than discobolus 90° (gut phase 1) 55 C. b. with at least 90° bend or partial s-shaped 61(60). Principal dorsal fin rays loop (gut phase 2) 62 a. absent ...... 278 c. with full loop (s-shape to near anterior b. present (at least one) but full comple- end of visceral cavity) but with neither ment incomplete or unclearly formed . 139 limb of loop completely across over C. present with full (adult) complement ventral midline (gut phase 3) C. discobolus clearly formed and countable (principal fin rays are sufficiently formed when the 55 (54). Dorsal surface lateral to midline from last principal ray, which consists of two shortly behind head to about 2/3 separate ray elements or "branches" distance to last myomeres with based on the most posterior pterygio- a. distinct continuous or nearly continuous phore, is well defined) ...... 171 lines of melanophores along (parallel to) each side of dorsal midline (Figs. 17, 62 (54). Dorsal surface lateral to midline from 59) 56 shortly behind head to about 2/3 b. distinctly shorter or discontinuous lines distance to last myomeres with of melanophores along one or both sides a. distinct continuous or nearly continuous of dorsal midline (Fig. 16) 59 lines of melanophores along (parallel

58 to) each side of dorsal midline (Fig. 69 (68). Principal dorsal fin rays 17) C. ardens...... a. absent ...... 278 b. distinctly shorter or discontinuous lines b. present (at least one) but full comple- of melanophores along one or both sides ment incomplete or unclearly formed . 143 of dorsal midline or with no distinct c. present with full (adult) complement lines of melanophores along either side clearly formed and countable (principal of dorsal midline (Figs. 44, 45) 63 fin rays are sufficiently formed when the last principal ray, which consists of two 63 (62). Pigmentation of peritoneum separate ray elements or "branches" a. absent on lateral and ventro-lateral sur- based on the most posterior pterygio- faces or present on lateral surfaces only phore, is well defined) ...... 183 (Figs. 17, 18, 44) 64 b. at least sparse or patchy on lateral and 70 (66). Melanophores in lines lateral (and ventro-lateral surfaces (Fig. 45) parallel) to dorsal midline between C. discobolus head and 2/3 distance to last myomeres mostly in 64 (36,60,63). Principal dorsal fin rays a. single file (Figs. 17, 87) 71 a. absent C ardens b. obliquely oriented pairs or groups b. present (at least one) but full comple- resulting in a "herring bone" or "tractor ment incomplete or unclearly formed . 146 tread" pattern (Fig. 59) C. laapinnis c. present with full (adult) complement clearly formed and countable (principal 71 (66,70). Pigmentation of peritoneum fin rays are sufficiently formed when the a. absent on lateral and ventro-lateral last principal ray, which consists of two surfaces (Figs. 17, 44, 59, 87) 72 separate ray elements or "branches" b. at least sparse or patchy on lateral based on the most posterior pterygio- surfaces only (Fig. 18) 79 phore, is well defined) ...... 171 c. at least sparse or patchy on lateral and ventro-lateral surfaces (Fig. 45) 65 (44). Gut (Fig. 5) C. discobolus a. essentially straight or with bend less than 90° (gut phase 1) 66 72 (71). Principal dorsal fm rays b. with at least 90° bend or partial s-shaped a. absent ...... 278 loop (gut phase 2) 73 b. present (at least one) but full comple- c. with full loop (s-shape to near anterior ment incomplete or unclearly formed . 136 end of visceral cavity) but with neither c. present with full (adult) complement limb of loop completely across over ven- clearly formed and countable (principal tral midline (gut phase 3) . . . C. discobolus fin rays are sufficiently formed when the last principal ray, which consists of two 66 (65). Dorsal surface lateral to midline from separate ray elements or "branches" shortly behind head to about 2/3 based on the most posterior pterygio- distance to last myomeres with phore, is well defined) ...... 169 a. distinct continuous or nearly continuous lines of melanophores along (parallel to) 73 (65). Dorsal surface lateral to midline from each side of dorsal midline (Figs. 17, shortly behind head to about 2/3 59) 67 distance to last myomeres with b. distinctly shorter or discontinuous lines a. distinct continuous or nearly continuous of melanophores along one or both sides lines of melanophores along (parallel to) of dorsal midline (Fig. 87) 70 each side of dorsal midline (Fig. 17) . . . 76 c. no distinct lines of melanophores along b. distinctly shorter or discontinuous lines either side of dorsal midline (Fig. 45) . . 71 of melanophores along one or both sides of dorsal midline or with no distinct 67 (66). Melanophores in lines lateral (and lines of melanophores along either side parallel) to dorsal midline between of dorsal midline (Figs. 45, 87) 74 head and 2/3 distance to last myomeres mostly in 74 (73). Pigmentation of peritoneum a. single file (Figs. 17, 87) 68 a. absent on lateral and ventro-lateral sur- b. obliquely oriented pairs or groups result- faces or present on lateral surfaces only ing in a "herring bone" or "tractor tread" (Figs. 17, 18, 44, 87) 79 pattern (Fig. 59) C. latipinnis b. at least sparse or patchy on lateral and ventro-lateral surfaces (Fig. 45) 68 (67). Pigmentation of peritoneum C. discobolus a. absent on lateral and ventro-lateral surfaces (Figs. 17, 59, 87) 69 75(44). Dorsal surface lateral to midline from b. at least sparse or patchy on lateral sur- shortly behind head to about 2/3 faces (Fig. 18) 76 distance to last myomeres with

59 a. distinct continuous or nearly continuous a. essentially straight or with bend less 0 lines of melanophores along (parallel than 90 (gut phase 1) 104 to) each side of dorsal midline (Fig. b. with at least 900bend or partial s-shaped 17) 76 loop (gut phase 2) 82 b. distinctly shorter or discontinuous lines c. with full loop (s-shape to near anterior of melanophores along one or both sides end of visceral cavity) but with neither of dorsal midline or with no distinct limb of loop completely across ventral lines of melanophores along either side midline (gut phase 3) or with at least of dorsal midline (Figs. 45, 87) 77 one limb of loop fully across ventral midline but not yet with both limbs 76 (68,73,75). Principal dorsal fin rays across fully to opposite side (gut phase a. absent ...... C. ardens 4) C. discobolus b. present (at least one) but full complement incomplete or unclearly formed . 130 82 (81). Dorsal surface lateral to midline from c. present with full (adult) complement shortly behind head to about 2/3 clearly formed and countable (principal distance to last myomeres with fm rays are sufficiently formed when the a. distinct continuous or nearly continuous last principal ray, which consists of two lines of melanophores along (parallel to) separate ray elements or "branches" each side of dorsal midline (Figs. 30, based on the most posterior pterygio- 31) C commersoni phore, is well defined) ...... 183 b. distinctly shorter or discontinuous lines of melanophores along one or both sides 77 (75). Gut (Fig. 5) of dorsal midline or with no distinct a. essentially straight or with bend less than lines of melanophores 0 0 along either side 90 (gut phase 1) or with at least 90 of dorsal midline (Figs. 72, 73) 83 bend or partial s-shaped loop (gut phase 2) 78 83 (82). Melanophores in lines lateral (and b. with full loop (s-shape to near anterior parallel) to dorsal midline between end of visceral cavity) but with neither head and 2/3 distance to last limb of loop completely across over myomeres mostly in ventral midline (gut phase 3) C. discobolus a. single file (Figs. 31, 33) 84 b. obliquely oriented pairs or groups 78 (77). Pigmentation of peritoneum resulting in a "herring bone" or "tractor a. absent on lateral and ventro-lateral sur- tread" pattern (Figs. 30, 59) C. commersoni faces or present on lateral surfaces only (Figs. 17, 18, 44, 87) 79 84 (83). Pigmentation of peritoneum b. at least sparse or patchy on lateral and a. absent on lateral and ventro-lateral ventro-lateral surfaces (Fig. 45) surfaces or present on lateral surfaces C. discobolus only (Figs. 30, 31, 44) 85 b. at least sparse or patchy on lateral and 79 (71,74,78). Principal dorsal fin rays ventro-lateral surfaces (Figs. 45, 73) .. . 86 a. absent ...... C. ardens b. present (at least one) but full comple- 85 (84). Principal dorsal fin rays ment incomplete or unclearly formed . 127 a. present (at least one) but full comple- c. present with full (adult) complement ment incomplete or unclearly formed clearly formed and countable (principal C commersoni fm rays are sufficiently formed when the b. present with full (adult) complement last principal ray, which consists of two clearly formed and countable (principal separate ray elements or "branches" fin rays are sufficiently formed when the based on the most posterior pterygio- last principal ray, which consists of two phore, is well defined) ...... 169 separate ray elements or "branches" based on the most posterior pterygio- 80 (1). Ventral midline from shortly behind phore, is well defined) ...... 161 heart region to near vent with a. -21. melanophores in a continuous or 86 (84). Principal dorsal fin rays nearly continuous line or narrow band a. present (at least one) but full comple- (if midline pigment extends into bran- ment incomplete or unclearly formed . 119 chial region anterior to heart, most b. present with full (adult) complement probably C. commersoni) (Figs. 31, 73) 104 clearly formed and countable (principal b. .>_.-21 melanophores in a shorter or a fm rays are sufficiently formed when the distinctly discontinuous line (Fig. 45) . 81 last principal ray, which consists of two c. 7-20 melanophores (Fig. 17) 87 separate ray elements or "branches" d. 1-6 melanophores (Fig. 59) 93 based on the most posterior pterygio- e. no pigment (Fig. 87) 96 phore, is well defined) ...... 158

81 (80). Gut (Fig. 5) 87 (80). Gut (Fig. 5)

60 a. essentially straight or with bend less than b. with at least 90° bend or partial s-shaped 90° (gut phase 1) 88 loop (gut phase 2) 97 b. with at least 90° bend or partial s-shaped c. with full loop (s-shape to near anterior loop (gut phase 2) 90 end of visceral cavity) but with neither c. with full loop (s-shape to near anterior limb of loop completely across ventral end of visceral cavity) but with neither midline (gut phase 3) or with at least limb of loop completely across ventral one limb of loop fully across ventral midline (gut phase 3) or with at least midline but not yet with both limbs one limb of loop fully across ventral across fully to opposite side (gut phase midline but not yet with both limbs 4) C. discobolus across fully to opposite side (gut phase 4) C. discobolus 94 (93). Pigmentation of peritoneum a. absent on lateral and ventro-lateral sur- 88 (87). Pigmentation of peritoneum faces (Figs. 17, 59, 87) 95 a. absent on lateral and ventro-lateral sur- b. at least sparse or patchy on lateral surfaces (Figs. 17, 59) 89 faces only (Fig. 18) 98 b. at least sparse or patchy on lateral surfaces only (Fig. 18) C. ardens 95 (94). Principal dorsal fin rays a. present (at least one) but full comple- 89 (88). Principal dorsal fin rays ment incomplete or unclearly formed . 143 a. present (at least one) but full comple- b. present with full (adult) complement ment incomplete or unclearly formed . 150 clearly formed and countable (principal b. present with full (adult) complement fin rays are sufficiently formed when the clearly formed and countable (principal last principal ray, which consists of two fin rays are sufficiently formed when the separate ray elements or "branches" last principal ray, which consists of two based on the most posterior pterygio- separate ray elements or "branches" phore, is well defined) ...... 183 based on the most posterior pterygiophore, is well defined) ...... C. ardens 96 (80). Gut (Fig. 5) a. essentially straight or with bend less 90 (87). Dorsal surface lateral to midline from than 90. (gut phase 1) 98 shortly behind head to about 2/3 b. with at least 90° bend or partial s-shaped distance to last myomeres with loop (gut phase 2) 97 a. distinct continuous or nearly continuous c. with full loop (s-shape to near anterior lines of melanophores along (parallel to) end of visceral cavity) but with neither each side of dorsal midline (Fig. 17) limb of loop completely across ventral C. ardens midline (gut phase 3) or with at least b. distinctly shorter or discontinuous lines one limb of loop fully across ventral of melanophores along one or both sides midline but not yet with both limbs of dorsal midline or with no distinct across fully to opposite side (gut phase lines of melanophores along either side 4) C. discobolus of dorsal midline (Figs. 44, 45) 91 97 (93,96). Dorsal surface lateral to .midline 91(90). Pigmentation of peritoneum from shortly behind head to about a. absent on lateral and ventro-lateral sur- 2/3 distance to last myomeres with faces or present on lateral surfaces only a. distinct continuous or nearly continuous (Figs. 17, 18, 44) 92 lines of melanophores along (parallel to) b. at least sparse or patchy on lateral and each side of dorsal midline (Fig. 17) . . . 98 ventro-lateral surfaces (Fig. 45) b. distinctly shorter or discontinuous lines C. discobolus of melanophores along one or both sides of dorsal midline or with no distinct 92 (91). Principal dorsal fin rays lines of melanophores along either side a. present (at least one) but full comple- of dorsal midline (Figs. 45, 87) 99 ment incomplete or unclearly formed ...... C. ardens 98 (94,96,97). Principal dorsal fin rays b. present with full (adult) complement a. present (at least one) but full comple- clearly formed and countable (principal ment incomplete or unclearly formed . 130 fm rays are sufficiently formed when the b. present with full (adult) complement last principal ray, which consists of two clearly formed and countable (principal separate ray elements or "branches" fin rays are sufficiently formed when the based on the most posterior pterygio- last principal ray, which consists of two phore, is well defined) ...... 171 separate ray elements or "branches" based on the most posterior pterygio- 93 (80). Gut (Fig. 5) phore, is well defined) ...... 183 a. essentially straight or with bend less than 90° (gut phase 1) 94 99 (97). Pigmentation of peritoneum

61 a. absent on lateral and ventro-lateral 105 (104). Melanophores in lines lateral (and surfaces or present on lateral surfaces parallel) to dorsal midline between only (Figs. 17, 18, 44, 87) 100 head and 2/3 distance to last myo- b. at least sparse or patchy on lateral and meres mostly in ventro-lateral surfaces (Fig. 45) a. single file (Figs. 31, 73) 106 C. discobolus b. obliquely oriented pairs or groups resulting in a "herring bone" or "tractor tread" 100 (99). Principal dorsal fin rays pattern (Figs. 30, 59) C commersoni a. present (at least one) but full complement incomplete or unclearly formed . 130 106 (104,105). Pigmentation of peritoneum b. present with full (adult) complement a. absent on lateral and ventro-lateral clearly formed and countable (principal surfaces or present on lateral surfaces fin rays are sufficiently formed when the only (Figs. 30, 31) C commersoni last principal ray, which consists of two b. at least sparse or patchy on lateral and separate ray elements or "branches" ventro-lateral surfaces (Fig. 73) 107 based on the most posterior pterygiophore, is well defined) ...... 169 107 (30,106). Principal dorsal fin rays a. present (at least one) but full comple- 101 (1). Ventral midline from shortly behind ment incomplete or unclearly formed . 119 heart region to near vent with b. present with full (adult) complement a. melanophores in a continuous or clearly formed and countable (principal nearly continuous line or narrow band fin rays are sufficiently formed when the (if midline pigment extends into bran- last principal ray, which consists of two chial region anterior to heart, most separate ray elements or "branches" probably C. commersoni) (Figs. 31, 73) 102 based on the most posterior pterygio- b. ?_-21 melanophores in a shorter or a phore, is well defined) ...... 164 distinctly discontinuous line (Fig. 45) . . 103 108 (101). Gut (Fig. 5) c. 7-20 melanophores (Fig. 17) 108 a. essentially straight or with bend less d. 1-6 melanophores (Fig. 59) 111 than 9O to (gut phase 1) or with at least no pigment (Fig. 87) 114 e. 90t o bend or partial s-shaped loop (gut phase 2) 109 102 (101). Gut (Fig. 5) b. with full loop (s-shape to near anterior a. essentially straight or with bend less than 0 end of visceral cavity) but with neither 90 (gut phase 1) C. platyrhynchus limb of loop completely across ventral b. with at least 90° bend or partial s-shaped midline (gut phase 3) or with at least loop (gut phase 2) 104 one limb of loop fully across ventral midline but not yet with both limbs 103 (101). Gut (Fig. 5) across fully to opposite side (gut phase a. essentially straight or with bend less than 4) C. discobolus 90° (gut phase 1) C platythynchus b. with at least 90° bend or partial s-shaped 109 (108). Pigmentation of peritoneum loop (gut phase 2) 104 a. absent on lateral and ventro-lateral c. with full loop (s-shape to near anterior surfaces (Figs. 17, 59) 110 end of visceral cavity) but with neither b. at least sparse or patchy on lateral limb of loop completely across ventral surfaces only (Fig. 18) C. ardens midline (gut phase 3) or with at least one limb of loop fully across ventral 110 (109). Principal dorsal fin rays midline but not yet with both limbs a. present (at least one) but full comple- across fully to opposite side (gut phase ment incomplete or unclearly formed 4) C. discobolus ...... C. laapinnis b. present with full (adult) complement 104 (80,81,102,103). Dorsal surface lateral to dearly formed and countable (principal midline from shortly behind head fin rays are sufficiently formed when the to about 2/3 distance to last myo- last principal ray, which consists of two meres with separate ray elements or "branches" a. distinct continuous or nearly continuous based on the most posterior pterygio- lines of melanophores along (parallel to) phore, is well defined) ...... 179 each side of dorsal midline (Figs. 30, 31) C commersoni 111 (101). Gut (Fig. 5) a. essentially straight or with bend less b. distinctly shorter or discontinuous lines 0 of melanophores along one or both sides than 90 (gut phase 1) or with at least of dorsal midline or (Figs. 72, 73) . . . . 105 90° bend or partial s-shaped loop (gut c. no distinct lines of melanophores along phase 2) 112 either side of dorsal midline (Figs. 44, b. with full loop (s-shape to near anterior 45) 106 end of visceral cavity) but with neither

62 limb of loop completely across ventral 119 (14,86,107). Full complement of dorsal fm midline (gut phase 3) or with at least one pterygiophores (same number as limb of loop fully across ventral midline but adult complement of principal not yet with both limbs across fully to dorsal fin rays which develop opposite side (gut phase 4) . . . C. discobolus subsequent to the pterygiophores) a. incompletely or unclearly formed ... 187 112 (111). Pigmentation of peritoneum b. clearly formed and countable ...... 120 a. absent on lateral and ventro-lateral surfaces (Figs. 17, 59, 87) 113 120 (119). Number of dorsal fin pterygiophores b. at least sparse or patchy on lateral a. 9 C. platyrhynchus surfaces only (Fig. 18) 115 b. 10-12 121 c. 13 C commersoni 113 (112). Principal dorsal fin rays a. present (at least one) but full comple- 121 (120). Length of base of dorsal fin (origin ment incomplete or unclearly formed . 154 to insertion of dorsal fin) b. present with full (adult) complement a. 11% SL C. plaiyrhynchus clearly formed and countable (principal b. 12-13% SL 187 fin rays are sufficiently formed when the c. 14% SL C commersoni last principal ray, which consists of two separate ray elements or "branches" 122 (18,34). Full complement of dorsal fm ptery- based on the most posterior pterygio- giophores (same number as adult phore, is well defined) ...... 175 complement of principal dorsal fin rays which develop subsequent to 114 (101). Gut (Fig. 5) the pterygiophores) a. essentially straight or with bend less than a. incompletely or unclearly formed 189 ° 90° (gut phase 1) or with at least 90 b. clearly formed and countable 123 bend or partial s-shaped loop (gut phase 2) 115 123 (122). Number of dorsal fin pterygiophores b. with full loop (s-shape to near anterior a. 9 126 end of visceral cavity) but with neither b. 10-12 124 limb of loop completely across ventral c. 13 C. commersoni midline (gut phase 3) or with at least one limb of loop fully across ventral 124 (123). Length of base of dorsal fin (origin but not yet with both limbs midline to insertion of dorsal fm) across fully to opposite side (gut phase a. 11% SL 191 4) C. discobolus b. 12-13% SL 189 c. 14% SL 185 115 (112,114). Principal dorsal fin rays a. present (at least one) but full complement incomplete or unclearly formed 125 (19,53). Full complement of dorsal fin ptery- ...... X. texanus giophores (same number as adult complement of principal dorsal fin b. present with full (adult) complement clearly formed and countable (principal rays which develop subsequent to pterygiophores) fin rays are sufficiently formed when the the 191 last principal ray, which consists of two a. incompletely or unclearly formed . 126 separate ray elements or "branches" b. clearly formed and countable based on the most posterior pterygiophore, is well defined) ...... 183 126 (123,125). Length of base of dorsal fin (origin to insertion of dorsal fin) 116 (6,52). Full complement of dorsal fin ptery- a. 11-13% SL 191 giophores (same number as adult b. 14% SL C. discobolus complement of principal dorsal fin rays which develop subsequent to 127 (41,79). Full complement of dorsal fin ptery- the pterygiophores) giophores (same number as adult a. incompletely or unclearly formed 185 complement of principal dorsal fin b. clearly formed and countable ...... 117 rays which develop subsequent to the pterygiophores) 117 (116). Number of dorsal fin pterygiophores a. incompletely or unclearly formed .. . . 197 a. 9 C. discobolus b. clearly formed and countable 128 b. 10-12 118 c. 13 C commersoni 128 (127). Number of dorsal fin pterygiophores a. 9 C. discobolus 118 (117). Length of base of dorsal fin (origin b. 10-11 148 to insertion of dorsal fin) c. 12 129 a. 11% SL C. discobolus d. 13-14 132 b. 12-14% SL 185 e. 15-16 X. tetanus

63 129 (128). Length of base of dorsal fin (origin to 138 (137). Length of base of dorsal fin (origin insertion of dorsal fin) to insertion of dorsal fin) a. 11% SL C. discobolus a. 11% SL C. discobolus b. 12-14% SL 149 b. 12-14% SL 142 c. 15% SL C. ardens c. 15% SL 153 d. 16-18% SL X. texanus d. 16-17% SL 157 e. 18% SL X. texanus 130 (39,76,98,100). Full complement of dorsal fm pterygiophores (same number as 139 (61). Full complement of dorsal fin ptery- adult complement of principal dorsal giophores (same number as adult fin rays which develop subsequent complement of principal dorsal fin to the pterygiophores) rays which develop subsequent to a. incompletely or unclearly formed . . . . 195 the pterygiophores) b. clearly formed and countable ...... 131 a. incompletely or unclearly formed . . . . 201 b. clearly formed and countable ...... 140 131 (130). Number of dorsal fm pterygiophores a. 10-11 C. ardens 140 (139). Number of dorsal fin pterygiophores b. 12-14 132 a. 9 C. discobolus c. 15-16 X. texanus b. 10 148 c. 11-12 141 132 (128,131). Length of base of dorsal fin d. 13-14 152 (origin to insertion of dorsal fm) a. 12-15% SL; length from anterior margin 141 (137,140). Length of base of dorsal fin of snout to insertion of dorsal fin 60- (origin to insertion of dorsal fin) 63% SL C. ardens a. 11% SL C. discobolus b. 16-18% SL; length from anterior margin b. 12-14% SL 142 of snout to insertion of dorsal fin 65- c. 15% SL 153 67% SL X. texanus d. 16-17% SL C. latipinnis

133 (42). Full complement of dorsal fin ptery- 142 (138,141). Length from anterior margin of giophores (same number as adult snout to insertion of dorsal fin complement of principal dorsal fin a. 60% SL C. ardens rays which develop subsequent to b. 61% SL 193 the pterygiophores) c. 62-63% SL 201 a. incompletely or unclearly formed . . . . 209 d. 64% SL 207 b. clearly formed and countable ...... 134 e. 65-67% SL C. latipinnis

134 (133). Number of dorsal fin pterygiophores 143 (69,95). Full complement of dorsal fin ptery- a. 9-11 C. discobolus giophores (same number as adult b. 12 ...... 135 complement of principal dorsal fin c. 13-16 X. texanus rays which develop subsequent to the pterygiophores) 135 (134). Length of base of dorsal fin (origin a. incompletely or unclearly formed . . . . 203 to insertion of dorsal fin) b. clearly formed and countable ...... 144 a. 11-14% SL; length from anterior margin of snout to insertion of dorsal fin 61- 144 (143). Number of dorsal fin pterygiophores 64% SL C. discobolus a. 10 C. ardens b. 16-18% SL; length from anterior margin b. 11 152 of snout to insertion of dorsal fm 65- c. 12-14 145 67% SL X. texanus d. 15-16 X. texanus

136 (72). Full complement of dorsal fin ptery- 145 (137,144). Length of base of dorsal fin giophores (same number as adult (origin to insertion of dorsal fin) complement of principal dorsal fin a. 12-15% SL 153 rays which develop subsequent to b. 16-17% SL 157 the pterygiophores) c. 18% SL X. texanus a. incompletely or unclearly formed . . . . 205 b. clearly formed and countable ...... 137 146 (22,26,64). Full complement of dorsal fin pterygiophores (same number as 137 (136). Number of dorsal fin pterygiophores adult complement of principal dor- a. 9 C. discobolus sal fm rays which develop subse- b. 10 ...... 148 quent to the pterygiophores) c. 11 141 a. incompletely or unclearly formed 193 d. 12 ...... 138 b. clearly formed and countable ...... 147 e. 13-14 145 f. 15-16 X. texanus 147 (146). Number of dorsal fin pterygiophores

64 a. 9 C. discobolus a. 9 167 b. 10-12 148 b. 10-12 159 c. 13-14 C. ardens c. 13 C. commersoni

148 (128,137,140,147). Length of base of dorsal 159 (158). Length of base of dorsal fin (origin fin (origin to insertion of dorsal fin) to insertion of dorsal fin) a. 11% SL C. discobolus a. 11% SL 168 b. 12-14% SL 149 b. 12-13% SL 160 c. 15% SL C ardens c. 14% SL 163

149 (129,148). Length from anterior margin of 160 (159). Dorsal fin length snout to insertion of dorsal fin a. 11-15% SL 192 a. 60% SL C. ardens b. 16-17% SL 186 b. 61-63% SL 193 c. 64% SL C. discobolus 161 (52,85). Number of principal dorsal fin rays a. 9 C. discobolus 150 (58,89). Full complement of dorsal fin ptery- b. 10-12 162 giophores (same number as adult c. 13 C commersoni complement of principal dorsal fin rays which develop subsequent to 162 (161). Length of base of dorsal fin (origin the pterygiophores) to insertion of dorsal fin) a. incompletely or unclearly formed ... 199 a. 11% SL C. discobolus b. clearly formed and countable ...... 151 b. 12-14% SL 163

151 (150). Number of dorsal fin pterygiophores 163 (159,162). Dorsal fin length a. 10 C. ardens a. 11-15% SL C. discobolus b. 11-14 152 b. 16-17% SL 186

152 (140,144,151). Length of base of dorsal fm 164 (107). Number of principal dorsal fin rays (origin to insertion of dorsal fin) a. 9 C platyrhynchus a. 12-15% SL 153 b. 10-12 165 b. 16-17% SL C. latipinnis c. 13 C commersoni

153 (138,141,145,152). Length from anterior 165 (164). Length of base of dorsal fm (origin margin of snout to insertion of to insertion of dorsal fin) dorsal fin a. 11% SL C. platyrhynchus a. 60-61% SL C. ardens b. 12-13% SL 166 b. 62-63% SL 199 c. 14% SL C. commersoni c. 64-67% SL C. latipinnis 166 (165). Dorsal fin length a. 11-15% SL C. platyrhynchus 154 (113). Full complement of dorsal fin ptery- b. 16-17% SL C commersoni giophores (same number as adult complement of principal dorsal fin 167 (53,158). Length of base of dorsal fin (origin rays which develop subsequent to to insertion of dorsal fin) the pterygiophores) a. 11-13% SL 168 a. incompletely or unclearly formed ...... 292 b. 14% SL C. discobolus b. clearly formed and countable ...... 155 168 (159,167). Dorsal fin length 155 (154). Number of dorsal fin pterygiophores a. 11-15% SL 192 a. 11 C. latipinnis b. 16-17% SL C. discobolus b. 12-14 156 c. 15-16 X. texanus 169 (72,79,100). Number of principal dorsal fin rays 156 (155). Length of base of dorsal fin (origin a. 9 C. discobolus to insertion of dorsal fin) b. 10-11 172 a. 12-15% SL C. latipinnis c. 12 170 b. 16-17% SL 157 d. 13-14 184 c. 18% SL X. teranus e. 15-16 X. texanus

157 (138,145,156). Length from anterior margin 170 (169). Length of base of dorsal fin (origin of snout to insertion of dorsal fin to insertion of dorsal fin) a. 62-64% SL C. latipinnis a. 11% SL C. discobolus b. 65-67% SL 292 b. 12-14% SL 173 c. 15% SL C. ardens 158 (34,86). Number of principal dorsal fm rays d. 16-18% SL X. texanus

65 171 (41,61,64,92). Number of principal dorsal b. 12-14 184 fm rays c. 15-16 X. teranus a. 9 C. discobolus b. 10-12 172 184 (169,183). Length of base of dorsal fin c. 13-14 C. ardens (origin to insertion of dorsal fin) a. 12-15% SL; length from anterior margin 172 (169,171). Length of base of dorsal fin of snout to insertion of dorsal fin 60- (origin to insertion of dorsal fin) 63% SL; dorsal fin length 14-16% SL a. 11% SL C. discobolus C. ardens b. 12-14% SL 173 b. 16-18% SL; length from anterior margin c. 15% SL C. ardens of snout to insertion of dorsal fin 65- 67% SL; dorsal fin length 18-21% SL 173 (170,172). Length from anterior margin of X. texanus snout to insertion of dorsal fin a. 60% SL C. ardens 185 (116,118,124). Pelvic fin buds b. 61-63% SL 174 a. absent ...... 218 c. 64% SL C. discobolus b. present ...... 186

174 (173). Dorsal fin length 186 (160,163,185). Length from anterior margin a. 11-13% SL C. discobolus of snout to origin of pelvic fin b. 14-17% SL 194 a. 52% SL C commersoni b. 53-54% SL 218 175 (113). Number of principal dorsal fin rays c. 55-57% SL C. discobolus a. 10 C. ardens b. 11 180 187 (119,121,133). Pelvic fm buds c. 12-14 176 a. absent ...... 225 d. 15-16 X. texanus b. present ...... 188

176 (175). Length of base of dorsal fin (origin 188 (187). Length from anterior margin of snout to insertion of dorsal fin) to origin of pelvic fin a. 12-15% SL 181 a. 52-54% SL 225 b. 16-17% SL 177 b. 55-56% SL C platyrhynchus c. 18% SL X. tetanus 189 (122,124). Pelvic fin buds 177 (176). Length from anterior margin of snout a. absent ...... 211 to insertion of dorsal fin b. present ...... 190 a. 62-64% SL C. latipinnis b. 65-67% SL 178 190 (189). Length from anterior margin of snout to origin of pelvic fin 178 (177). Dorsal fin length a. 52% SL C. commersoni a. 15-17% SL C. latipinnis b. 53-54% SL 211 b. 18-21% SL 292 c. 55-56% SL 231 d. 57% SL C. discobolus 179 (110). Number of principal dorsal fin rays a. 10 C ardens 191 (124,125,126). Pelvic fin buds b. 11-14 180 a. absent ...... 231 b. present ...... 192 180 (175,179). Length of base of dorsal fin (origin to insertion of dorsal fin) 192 (160,168,191). Length from anterior margin a. 12-15% SL 181 of snout to origin of pelvic fin b. 16-17% SL C. latipinnis a. 52% SL C platyrhynchus b. 53-56% SL 231 181 (176,180). Length from anterior margin of c. 57% SL C. discobolus snout to insertion of dorsal fin a. 60-61% SL C. ardens 193 (142,146,149). Pelvic fm buds b. 62-63% SL 182 a. absent ...... 271 c. 64-67% SL C. latipinnis b. present ...... 194

182 (181). Dorsal fm length 194 (174,193). Length from anterior margin of a. 14% SL C. ardens snout to origin of pelvic fm b. 15-16% SL 200 a. 50-52% SL C. ardens c. 17-21% SL C. latipinnis b. 53% SL 271 c. 54-57% SL C. discobolus 183 (69,76,95,98,115). Number of principal dorsal fin rays 195 (130). Pelvic fin buds a. 10-11 C ardens a. absent ...... 282

66 b. present ...... 196 b. 53-54% SL 287 c. 55-57% SL C. discobolus 1% (195). Length from anterior margin of snout to origin of pelvic fin 209 (133). Pelvic fin buds a. 50-53% SL 282 a. absent ...... 288 b. 54% SL X. tetanus b. present ...... 210 197 (127). Pelvic fm buds 210 (209). Length from anterior margin of snout a. absent ...... 248 to origin of pelvic fin b. present ...... 198 a. 50-52% SL X. texanus b. 53-54% SL 288 198 (197). Length from anterior margin of snout c. 55-57% SL C. discobolus to origin of pelvic fm a. 50-52% SL 282 211 (18,189,190). Longitudinal eye diameter b. 53% SL 248 a. 24-25% of head length 218 c. 54% SL 288 b. 26-34% of head length 212 d. 55-57% SL C. discobolus c. 35% of head length ...... C. platyrhynchus 199 (150,153). Pelvic fm buds 212 (211). Pigment over ventral to ventro-lateral a. absent ...... 278 surfaces of gill covers (opercula) b. present ...... 200 a. absent or present but not in distinct oblique rows (Figs. 30, 45, 72) 213 200 (182,199). Length from anterior margin of b. present in a distinct oblique row of 3 or snout to origin of pelvic fin more melanophores near or along ven- a. 50-53% SL 278 tral margin of one or both preopercles b. 54% SL C. latipinnis (Figs. 31, 73) 226 201 (139,142). Pelvic fin buds 213 (212). Pigment on ventral surface of heart a. absent ...... 255 region b. present ...... 202 a. absent (Fig. 45) C. discobolus b. present (Figs. 31, 44, 73) 214 202 (201). Length from anterior margin of snout to origin of pelvic fin 214 (213). Lateral surface of head posterior to a. 50-52% SL 278 eyes with b. 53% SL 255 a. melanophores. (Fig. 45) 234 c. 54% SL 287 b. L-6 melanophores (Figs. 31, 73) 215 d. 55-57% SL C. discobolus 215 (214). Developing dorsal fm with 203 (143). Pelvic fin buds a. few (- 5) or no melanophores (Fig. 45) 234 a. absent ...... 266 b. many (?:6) melanophores (Fig. 73; Fig. b. present ...... 204 31 by our observations should have more melanophores in the dorsal fin for speci- 204 (203). Length from anterior margin of snout mens of the size pertinent to this loop of to origin of pelvic fm the key) ...... 216 a. 50-53% SL 266 b. 54% SL 292 216 (215). Length from anterior margin of snout to posterior margin of vent 205 (136). Pelvic fin buds a. 76% SL C. discobolus a. absent ...... 236 b. 77% SL 235 b. present ...... 206 c. 78-80% SL 217 d. 81% SL 223 206 (205). Length from anterior margin of snout to origin of pelvic fm 217 (216). Number of myomeres to posterior a. 50-52% SL 266 margin of vent b. 53% SL 236 a. 32-33 C. platyrhynchus c. 54% SL 293 b. 34 230 d. 55-57% SL C. discobolus c. 35-37 309 d. 38-40 224 207 (142). Pelvic fin buds a. absent ...... 287 218 (6,185,186,211). Pigment over ventral to b. present ...... 208 ventro-lateral surfaces of gill covers (opercula) 208 (207). Length from anterior margin of snout a. absent or present but not in distinct to origin of pelvic fm oblique rows ...... 219 a. 50-52% SL C. lattpinnis b. present in a distinct oblique row of 3 or

67 more melanophores near or along ventral a. 32-33 C. platyrhynchus margin of one or both preopercles b. 34-37 230 C commersoni c. 38-40 C commersoni

219 (218). Pigment on ventral surface of heart 230 (217,229). Total number of myomeres region a. 43-47 C commersoni a. absent (Fig. 45) C. discobolus C. platyrhynchus b. present (Figs. 31, 44) 220 b. 48-49 C. commersoni

220 (219). Lateral surface of head posterior to 231 (19,190,191,192). Longitudinal eye diameter eyes with a. 24-25% of head length ...... C. discobolus a. melanophores (Fig. 45) . . C. discobolus b. 26-34% of head length ...... 232 b. L-6 melanophores (Fig. 31) 221 c. 35% of head length C platyrhynchus

221 (220). Developing dorsal fin with 232 (231). Pigment over ventral to ventro-lateral a. few (5) or no melanophores (Fig. 45) surfaces of gill covers (opercula) C. discobolus a. absent or present but not in distinct b. many (L-6) melanophores (Fig 31 by our oblique rows (Fig. 45) 233 observations should have more melano- b. present in a distinct oblique row of 3 or phores in the dorsal fin for specimens of more melanophores near or along ven- the size pertinent to this loop of the tral margin of one or both preopercles key) ...... 222 (Fig. 73) C platyrhynchus

222 (221). Length from anterior margin of snout 233 (232). Pigment on ventral surface of heart to posterior margin of vent region a. 76-77% SL C. discobolus a. absent (Fig. 45) C. discobolus b. 78-81% SL 223 b. present (Figs. 44, 73) 234

223 (216,222). Number of myomeres to 234 (214,215,233). Length from anterior margin posterior margin of vent of snout to posterior margin of vent a. 34 C commersoni a. 76% SL C. discobolus b. 35-40 224 b. 77-80% SL 235 c. 81% SL C. discobolus 224 (217,223). Total number of myomeres a. 43-46 C commersoni 235 (216,234). Number of myomeres to b. 47-49 C commersoni posterior margin of vent C. discobolus a. 32-34 C. platyrhynchus b. 35-37 310 225 (14,187,188). Longitudinal eye diameter c. 38-40 C. discobolus a. 24-25% of head length . . . . C. commersoni b. 26-34% of head length ...... 226 236 (205,206). Longitudinal eye diameter c. 35% of head length...... C. platyrhynchus a. 24-26% of head length ...... 237 b. 27-30% of head length ...... 238 226 (212,225). Lateral surface of head posterior c. 31-33% of head length ...... 239 to eyes with d. 34% of head length ...... 257 a. 5 melanophores (Fig. 45) C. platyrhynchus e. 35% of head length ...... 279 b. ?:6 melanophores (Figs. 31, 73) 227 f. 36-38% of head length ...... C. ardens

227 (226). Developing dorsal fin with 237 (236). Pigment over ventral to ventro-lateral a. few (5) or no melanophores (Fig. 45) . . . surfaces of gill covers (opercula) C. platyrhynchus a. absent or present but not in distinct b. many (-.6) melanophores (Fig. 73; Fig. oblique rows (Figs. 45, 59) 259 31 by our observations should have more b. present in a distinct oblique row of 3 or melanophores in the dorsal fin for speci- more melanophores near or along ven- mens of the size pertinent to this loop of tral margin of one or both preopercles the key) ...... 228 (Fig. 73) C. latipinnis

228 (227). Length from anterior margin of snout 238 (236). Pigment over ventral to ventro-lateral to posterior margin of vent surfaces of gill covers (opercula) a. 77% SL C. platyrhynchus a. absent or present but not in distinct b. 78-80% SL 229 oblique rows (Figs. 45, 59, 87) 241 c. 81% SL C commersoni b. present in a distinct oblique row of 3 or more melanophores near or along ven- 229 (228). Number of myomeres to posterior tral margin of one or both preopercles margin of vent (Fig. 73) 306

68 239 (236). Pigment over ventral to ventro-lateral b. 44-45 C. ardens surfaces of gill covers (opercula) X. texanus a. absent or present but not in distinct c. 46 C. ardens oblique rows (Figs. 16, 45, 59, 87) . . . . 240 C. latipinnis b. present in a distinct oblique row of 3 or X. texanus more melanophores near or along ven- d. 47-48 C. ardens tral margin of one or both preopercles C discobolus (Fig. 17) 267 C. latipinnis X. texanus 240 (239). Pigment on ventral surface of heart e. 49 C. discobolus region C. latipinnis a. absent (Figs. 45, 59) 241 X. texanus b. present (Figs. 17, 44, 58, 87) 244 248 (26,197,198). Longitudinal eye diameter 241 (238,240). Lateral surface of body below a. 24-26% of head length ...... C. discobolus horizontal myosepta (or lateral mid- b. 27-30% of head length ...... 289 line) exclusive of melanophores c. 31-33% of head length ...... 249 associated with horizontal myosepta, d. 34% of head length ...... 272 air bladder, visceral cavity (peri- e. 35-38% of head length ...... C. ardens toneum), or gut, a. unpigmented or with melanophores 249 (248). Pigment over ventral to ventro-lateral (Figs. 45, 59, 87) 242 surfaces of gill covers (opercula) b. pigmented with ?:6 melanophores (Fig a. absent or present but not in distinct 46) C. discobolus oblique rows (Figs. 16, 45, 87) 250 b. present in a distinct oblique row of 3 or 242 (241). Length from anterior margin of snout more melanophores near or along ven- to posterior margin of vent tral margin of one or both preopercles a. 76-77% SL 261 (Fig. 17) 283 b. 78-80% SL 243 c. 81% SL 304 250 (249). Pigment on ventral surface of heart d. 82-84% SL X. texanus region a. absent (Figs. 45, 88) 290 243 (242). Number of myomeres to posterior b. present (Figs. 17, 44, 87) 251 margin of vent a. 35 C. discobolus 251 (250). Lateral surface of body below hori- b. 36-40 303 zontal myosepta (or lateral midline) c. 41 X. texanus exclusive of melanophores associated with horizontal myosepta, air 244 (240). Lateral surface of body below hori- bladder, visceral cavity (peri- zontal myosepta (or lateral midline) toneum), or gut, exclusive of melanophores asso- a. unpigmented or with melanophores ciated with horizontal myosepta, air (Figs. 17, 45, 87) 252 bladder, visceral cavity (peri- b. pigmented with melanophores (Fig toneum), or gut, 46) C. discobolus a. unpigmented or with melanophores (Figs. 17, 45, 59, 87) 245 252 (251). Length from anterior margin of snout b. pigmented with melanophores (Fig to posterior margin of vent 46) C. discobolus a. 76-77% SL 276 b. 78-80% SL 253 245 (244). Length from anterior margin of snout c. 81% SL 304 to posterior margin of vent d. 82-84% SL X. texanus a. 76-77% SL 264 b. 78-80% SL 246 253 (252). Number of myomeres to posterior c. 81% SL 304 margin of vent d. 82-84% SL X. texanus a. 34 C. ardens b. 35 277 246 (245). Number of myomeres to posterior c. 36-38 254 margin of vent d. 39-40 305 a. 34 C. ardens e. 41 X. texanus b. 35 ...... 277 c. 36-38 247 254 (253). Total number of myomeres d. 39-40 303 a. 43 C. ardens e. 41 X. texanus b. 44-46 C. ardens X. texanus 247 (246). Total number of myomeres c. 47-48 C. ardens a. 43 C. ardens C. discobolus

69 X. texanus 263 (262). Length from anterior margin of snout d. 49 C. discobolus to posterior margin of vent X. texanus a. 76-80% SL 264 b. 81% SL C. discobolus 255 (201,202). Longitudinal eye diameter a. 24-30% of head length ...... 256 264 (245,263). Number of myomeres to poster- b. 31-34% of head length ...... 257 ior margin of vent c. 35% of head length ...... 279 a. 34 C. ardens d. 36-38% of head length ...... C. ardens b. 35 277 c. 36-38 265 256 (255). Pigment over ventral to ventro-lateral d. 39-40 301 surfaces of gill covers (opercula) a. absent or present but not in distinct 265 (264). Total number of myomeres oblique rows (Figs. 45, 59) 259 a. 43-45 C. ardens b. present in a distinct oblique row of 3 or b. 46 C. ardens more melanophores near or along ven- C. latipinnis tral margin of one or both preopercles c. 47-48 C. ardens (Fig. 17) C. latipinnis C discobolus C. latipinnis 257 (236,255). Pigment over ventral to d. 49 C. discobolus ventro-lateral surfaces of gill covers C. latipinnis (opercula) a. absent or present but not in distinct 266 (203,204,206). Longitudinal eye diameter oblique rows (Figs. 16, 45, 59) 258 a. 24-26% of head length ...... C. latipinnis b. present in a distinct oblique row of 3 or b. 27-30% of head length ...... 306 more melanophores near or along ven- c. 31-33% of head length ...... 267 tral margin of one or both preopercles d. 34-35% of head length ...... 279 (Fig. 17) 279 e. 36-38% of head length ...... C. ardens

258 (257). Pigment on ventral surface of heart 267 (239,266). Pigment on ventral surface of region heart region a. absent (Figs. 45, 59) 259 a. absent (Figs. 59, 88) 306 b. present (Figs. 17, 44, 58) 262 b. present (Figs. 17, 58, 87) 268

259 (237,256,258). Lateral surface of body below 268 (267). Length from anterior margin of snout horizontal myosepta (or lateral to posterior margin of vent midline) exclusive of melanophores a. 76-77% SL 280 associated with horizontal myosepta, b. 78-80% SL 269 air bladder, visceral cavity (peri- c. 81-84% SL X. texanus toneum), or gut, a. unpigmented or with melanophores 269 (268). Number of myomeres to posterior (Figs. 45, 59) 260 margin of vent b. pigmented with .of, melanophores (Fig a. 34-35 C. ardens 46) C. discobolus b. 36-38 270 c. 39-40 308 260 (259). Length from anterior margin of snout d. 41 X. texanus to posterior margin of vent a. 76-80% SL 261 270 (269). Total number of myomeres b. 81% SL C. discobolus a. 43 C. ardens b. 44-45 C. ardens 261 (242,260). Number of myomeres to X. texanus posterior margin of vent c. 46-48 C. ardens a. 35 C. discobolus C. latipinnis b. 36-40 301 X. texanus d. 49 C. latipinnis 262 (258). lateral surface of body below X. texanus horizontal myosepta (or lateral midline) exclusive of melanophores 271 (22,193,194). Longitudinal eye diameter associated with horizontal myosepta, a. 24-30% of head length ...... C. discobolus air bladder, visceral cavity (peri- b. 31-34% of head length ...... 272 toneum), or gut, c. 35-38% of head length ...... C. ardens a. unpigmented or with melanophores (Figs. 17, 45, 59) 263 272 (248,271). Pigment over ventral to b. pigmented with melanophores (Fig ventro-lateral surfaces of gill covers 46) C. discobolus (opercula)

70 a. absent or present but not in distinct b. 31-33% of head length ...... 283 oblique rows (Figs. 16, 45) 273 c. 34-38% of head length C ardens b. present in a distinct oblique row of 3 or more melanophores near or along ven- 283 (249,282). Pigment on ventral surface of tral margin of one or both preopercles heart region (Fig. 17) C ardens a. absent (Fig. 88) X. texanus b. present (Figs. 17, 87) 284 273 (272). Pigment on ventral surface of heart region 284 (283). Length from anterior margin of snout a. absent (Fig. 45) C. discobolus to posterior margin of vent b. present (Figs. 17, 44) 274 a. 76-77% SL C. ardens b. 78-80% SL 285 274 (273). Lateral surface of body below hori- c. 81-84% SL X. texanus zontal myosepta (or lateral midline) exclusive of melanophores asso- 285 (284). Number of myomeres to posterior ciated with horizontal myosepta, air margin of vent bladder, visceral cavity (peri- a. 34-35 C. ardens toneum), or gut, b. 36-38 286 a. unpigmented or with melanophores c. 41 X. texanus (Figs. 17, 45) 275 b. pigmented with melanophores (Fig 286 (285). Total number of myomeres 46) C. discobolus a. 43 C. ardens b. 44-48 C. ardens 275 (274). Length from anterior margin of snout X. texanus to posterior margin of vent c. 49 X. texanus a. 76-80% SL 276 b. 81% SL C. discobolus 287 (202,207,208). Longitudinal eye diameter a. 24-34% of head length ...... 294 276 (252,275). Number of myomeres to poster- b. 35% of head length ...... C. latipinnis ior margin of vent a. 34 C. ardens 288 (9,198,209,210). Longitudinal eye diameter b. 35-38 277 a. 24-26% of head length ...... C. discobolus c. 39-40 C. discobolus b. 27-33% of head length ...... 289 c. 34% of head length ...... C. discobolus 277 (246,253,264,276). Total number of myomeres a. 43-46 C. ardens 289 (248,288). Pigment over ventral to b. 47-48 C. ardens ventro-lateral surfaces of gill covers C discobolus (opercula) c. 49 C. discobolus a. absent or present but not in distinct oblique rows (Figs. 45, 87) 290 278 (58,61,69,72,199,200,202). Longitudinal eye b. present in a distinct oblique row of 3 or diameter more melanophores near or along ven- a. 24-30% of head length ...... C. latipinnis tral margin of one or both preopercles b. 31-35% of head length ...... 279 (Fig. 17) X. texanus c. 36-38% of head length C ardens 290 (250,289). Lateral surface of body below 279 (236,255,257,266,278). Pigment on ventral horizontal myosepta (or lateral surface of heart region midline) exclusive of melanophores a. absent (Fig. 59) C. latipinnis associated with horizontal myosepta, b. present (Figs. 17, 58) 280 air bladder, visceral cavity (peritoneum), or gut, 280 (268,279). Number of myomeres to a. unpigmented or with melanophores posterior margin of vent (Figs. 45, 87) 291 a. 34-35 C ardens b. pigmented with ?_-6 melanophores (Fig b. 36-38 281 46) C. discobolus c. 39-40 C. latipinnis 291 (290). Length from anterior margin of snout 281 (280). Total number of myomeres to posterior margin of vent a. 43-45 C ardens a. 76-77% SL C. discobolus b. 46-48 C ardens b. 78-81% SL 304 C. latipinnis c. 82-84% SL X. texanus c. 49 C. latipinnis 292(154,157,178,204). Longitudinal eye diameter 282 (24,39,41,195,196,198). Longitudinal eye a. 24-26% of head length ...... C. latipinnis diameter b. 27-33% of head length ...... 306 a. 27-30% of head length ...... X. texanus c. 34-35% of head length ...... C. latipinnis

71 293 (206). Longitudinal eye diameter 301 (261,264,300). Total number of myomeres a. 24-26% of head length ...... 294 a. 46 C. latipinnis b. 27-33% of head length ...... 297 b. 47-49 C. discobolus c. 34% of head length ...... 294 C. latipinnis d. 35% of head length ...... C. latipinnis 302 (299). Number of myomeres to posterior 294 (287,293). Pigment over ventral to margin of vent ventro-lateral surfaces of gill covers a. 35 C. discobolus (opercula) b. 36-40 303 a. absent or present but not in distinct c. 41 X. teranus oblique rows (Figs. 45, 59) 295 b. present in a distinct oblique row of 3 or 303 (243,246,302). Total number of myomeres more melanophores near or along ven- a. 44-45 X. texanus tral margin of one or both preopercles b. 46 C. latipinnis (Fig. 17) C. latipinnis X. texanus c. 47-49 C. discobolus 295 (294). Lateral surface of body below C. latipinnis horizontal myosepta (or lateral X. texanus midline) exclusive of melanophores associated with horizontal myosepta, air bladder, visceral cavity (peri- 304(242,245,252,291,299). Number of myomeres toneum), or gut, to posterior margin of vent a. unpigmented or with 15.5 melanophores a. 35 C. discobolus (Figs. 45, 59) 296 b. 36-40 305 b. pigmented with .>16 melanophores (Fig c. 41 X. texanus 46) C. discobolus 305 (253,304). Total number of myomeres 296 (295). Length from anterior margin of snout a. 44-46 X. texanus to posterior margin of vent b. 47-49 C. discobolus a. 76-80% SL 300 X. tetanus b. 81% SL C. discobolus 306 (238,266,267,292,297). Length from anterior 297 (293). Pigment over ventral to ventro-lateral margin of snout to posterior margin surfaces of gill covers (opercula) of vent a. absent or present but not in distinct a. 76-77% SL C. latipinnis oblique rows (Figs. 45, 59, 87) 298 b. 78-80% SL 307 b. present in a distinct oblique row of 3 or c. 81-84% SL X. texanus more melanophores near or along ventral margin of one or both preopercles 307 (306). Number of myomeres to posterior (Fig. 17) 306 margin of vent a. 36-40 308 298 (297). Lateral surface of body below b. 41 X. texanus horizontal myosepta (or lateral midline) exclusive of melanophores 308 (269,307). Total number of myomeres associated with horizontal myosepta, a. 44-45 X. texanus air bladder, visceral cavity (peri- b. 46-49 C. latipinnis toneum), or gut, X. texanus a. unpigmented or with 5 melanophores (Figs. 45, 59, 87) 299 b. pigmented with melanophores (Fig 309 (217). Total number of myomeres 46) C. discobolus a. 43-46 C. commersoni C. platyrhynchus 299 (298). Length from anterior margin of snout b. 47 C. commersoni to posterior margin of vent C. discobolus a. 76-77% SL 300 C. platyrhynchus b. 78-80% SL 302 c. 48-49 C. commersoni c. 81% SL 304 C. discobolus d. 82-84% SL X. texanus 310 (235). Total number of myomeres 300 (296,299). Number of myomeres to poster- a. 43-46 C. platyrhynchus ior margin of vent b. 47 C. discobolus a. 35 C. discobolus C. platyrhynchus b. 36-40 301 c. 48-49 C. discobolus

72 Skeletal Character Key for Postflexion Meso- d. 47 C. ardens larvae that have been cleared and prefer- C. commersoni ably stained for bone or cartilage (Fig. 6). C. discobolus C. latipinnis C. platyrhynchus 1. Standard length group (Fig. 4) X. texanus a. ?....18 mm C. latipinnis e. 48 C. ardens b. 17 mm 2 C. commersoni c. 16mm 3 C. discobolus C. latipinnis First (most anterior) interneural bone 2 (1). C. platyrhynchus (Fig. 8) f. 49-50 C. discobolus formed ...... 3 a. unclearly C. latipinnis large and fan-shaped across top X. teranus b. (rarely) C. platyrhynchus c. large and angular or anvil-shaped with a prominent posterior-directed projection or beak ...... 4 4 (2). Number of vertebrae (including 4 for d. small and blocky or angular with a small Weberian complex) to moderate posterior-directed projec- a. 44-46 C commersoni tion or beak ...... 5 b. 47-48 C. ardens C. commersoni 3 (1,2). Number of vertebrae (including 4 for C. latipinnis Weberian complex) C. 49-50 C. latipinnis a. 42-43 C. platyrhynchus b. 44 C commersoni C. platyrhynchus 5 (2). Number of vertebrae (including 4 for c. 45-46 C commersotzi Weberian complex) C. discobolus a. 42-44 C platyrhynchus C. platyrhynchus b. 45-50 C. discobolus X. texanus (rarely 49-50) C. platyrhynchus

Metalarvae -- adult complement of principal fin 3 (2). Pigmentation on lateral surfaces of rays present in dorsal, anal, and caudal fins, peritoneum but some preanal finfold remaining (Figs. a. absent (Figs. 19, 88, 89) 67 18, 19; definition abbreviated for species of b. sparse or patchy (Figs. 18, 32, 33) 72 concern; there may be rare metalarval 4 (1). Gut (Fig. 5) specimens in which all finfold is lost but a. essentially straight or with bend less not all pelvic fin rays or rudimentary caudal than 90° (gut phase 1) C. ardens fin rays are yet present). Separate skeletal b. with at least 90° bend or partial s-shaped character key at end for confirmation of loop (gut phase 2) 5 identity or further diagnosis of specimens c. with full loop (s-shape to near anterior cleared (and preferably stained) for bone. end of visceral cavity) but with neither limb of loop completely across over ventral midline (gut phase 3) 7 1. Standard length (SL; Fig. 4) d. with at least one limb of loop fully a. 15 mm 2 across ventral midline but not yet with b. 16 mm 4 both limbs across fully to opposite side c. 17 mm 9 (gut phase 4) to gut with both limbs of d. 18 mm 13 loop across midline fully to opposite side e. 19 mm 20 (four segments of gut crossing nearly f. 20 mm 28 perpendicular to body axis) or with 8. 21 mm 38 more extensive coil development (gut h. 22 mm 47 phase 5) C. discobolus i. 23 mm 52 j. 24 mm 53 5 (4). Pigmentation on lateral surfaces of k. 25 mm C. latipinnis peritoneum a. absent (Figs. 19, 88, 89) 67 2 (1). Gut (Fig. 5) b. sparse or patchy (Figs. 18, 32, 33, a. essentially straight or with bend less than 74) 6 90° (gut phase 1) C ardens b. with at least 90° bend or partial s-shaped 6 (5). Pigmentation on ventro-lateral surfaces loop (gut phase 2) 3 of peritoneum

73 a. absent (Fig. 18) 78 d. both limbs of loop across midline fully b. sparse or patchy (Figs. 33, 74) 85 to opposite side (four segments of gut crossing nearly perpendicular to body 7 (4). Pigmentation on lateral surfaces of axis) or with more extensive coil peritoneum development (gut phase 5) . . C. discobolus a. absent (Fig. 19) C commersoni b. sparse or patchy (Figs. 32, 33, 46, 74, 14 (13). Pigmentation on lateral surfaces of 75) 8 peritoneum a. absent (Fig. 19) 72 8 (7). Pigmentation on ventro-lateral surfaces b. sparse or patchy (Figs. 18, 32, 33) 15 of peritoneum a. absent (Fig. 19) 85 15 (14). Pigmentation on ventro-lateral surfaces b. sparse or patchy (Figs. 33, 46, 74, 75) . 81 of peritoneum a. absent (Fig. 18) 72 9 (1). Gut (Fig. 5) b. sparse or patchy (Fig. 33) . . C. commersoni a. essentially straight or with bend less than (gut phase 1) 16 (9,13). 90° 0 C. ardens Pigmentation on lateral surfaces of b. with at least 90 bend or partial s-shaped peritoneum loop (gut phase 2) 16 a. absent (Figs. 19, 88, 89) 67 c. with full loop (s-shape to near anterior b. sparse or patchy (Figs. 18, 32, 33) 17 end of visceral cavity) but with neither limb of loop completely across over 17 (16). Pigmentation on ventro-lateral surfaces ventral midline (gut phase 3) 10 of peritoneum d. with at least one limb of loop fully a. absent (Fig. 18) 72 across ventral midline but not yet with b. sparse or patchy (Figs. 33, 74) 18 both limbs across fully to opposite side (gut phase 4) to gut with both limbs of 18 (17). Pigmentation on ventral surface of loop across midline fully to opposite side Peritoneum (four segments of gut crossing nearly a. absent (Fig. 32; do not confuse peri- perpendicular to body axis) or with more toneal pigmentation with epidermal or extensive coil development (gut phase surface pigmentation) ...... 85 5) C. discobolus b. sparse or patchy (Figs. 74, 75) C platyrhynchus 10 (9). Pigmentation on lateral surfaces of peritoneum 19 (13). Pigmentation on lateral surfaces of a. absent (Figs. 88, 89) 73 peritoneum b. sparse or patchy (Figs. 32, 33, 46, 75) . 11 a. absent (Figs. 88, 89) X. texanus c. uniformly light to dark (Fig. 47) b. sparse or patchy (Fig. 75) . C. platyrhynchus C. discobolus c. uniformly light to dark (Fig. 47) C. discobolus 11(10). Pigmentation on ventro-lateral surfaces of peritoneum 20 (1). Gut (Fig. 5) with a. absent (Fig. 32) C commersoni a. at least 90° bend or partial s-shaped b. sparse or patchy (Figs. 33, 46, 75) 12 loop (gut phase 2) 21 c. uniformly light to dark (Fig. 47) b. full loop (s-shape to near anterior end C. discobolus of visceral cavity) but with neither limb of loop completely across over ventral 12 (11). Pigmentation on ventral surface of midline (gut phase 3) 22 peritoneum c. at least one limb of loop fully across a. absent (Fig. 32; do not confuse peri- ventral midline but not yet with both toneal pigmentation with epidermal or limbs across fully to opposite side (gut surface pigmentation) ...... 81 phase 4) 26 b. sparse or patchy (Figs. 46, 74) 88 d. both limbs of loop across midline fully to opposite side (four segments of gut 13 (1). Gut (Fig. 5) with crossing nearly perpendicular to body a. at least 90° bend or partial s-shaped loop axis) or with more extensive coil (gut phase 2) 14 development (gut phase 5) . . C. discobolus b. full loop (s-shape to near anterior end of visceral cavity) but with neither limb 21 (20). Mouth of loop completely across over ventral a. terminal (above bottom-of-eye level) midline (gut phase 3) 16 (Fig. 17) C. ardens c. at least one limb of loop fully across b. low terminal (at or below bottom-of-eye ventral midline but not yet with both level) to slightly subterminal (mouth, limbs across fully to opposite side (gut including upper lip, not the most anter- phase 4) 19 ior portion of snout) (Figs. 18, 60) .... 61

74 22 (20). Pigmentation on lateral surfaces of b. low terminal (at or below bottom-of-eye peritoneum level) to slightly subterminal (mouth, a. absent (Figs. 19, 60, 88, 89) 23 including upper lip, not the most anter- b. sparse or patchy (Figs. 18, 32, 33, 75) . 24 ior portion of snout) (Figs. 19, 60, 89) . 60

23 (22). Mouth 31(29). Pigmentation on ventro-lateral surfaces a. terminal (above bottom-of-eye level) of peritoneum (Figs. 17, 87) 68 a. absent (Fig. 18) 32 b. low terminal (at or below bottom-of-eye b. sparse or patchy (Fig. 33) 37 level) to slightly subterminal (mouth, c. uniformly light to dark (Fig. 75) including upper lip, not the most C. platyrhynchus anterior portion of snout) (Figs. 18, 60, &91)0 32 (31). Mouth a. terminal (above bottom-of-eye level) 24 (22). Pigmentation on ventro-lateral surfaces (Fig. 87) X. texanus of peritoneum b. low terminal (at or below bottom-of-eye a. absent (Figs. 18, 60) 25 level) to slightly subterminal (mouth, b. sparse or patchy (Fig. 33) . . C. commersoni including upper lip, not the most anter- c. uniformly light (Fig. 75) . . C. platyrhynchus ior portion of snout) (Figs. 19, 33, 60, 89) 58 25 (24). Mouth a. terminal (above bottom-of-eye level) 33 (28). Pigmentation on lateral surfaces of (Fig. 17) C ardens peritoneum b. low terminal (at or below bottom-of-eye a. absent (Figs. 19, 89) 34 level) to slightly subterminal (mouth, b. sparse or patchy (Figs. 18, 33, 75) 35 including upper lip, not the most anter- c. uniformly dark (Figs. 47, 48) C. discobolus ior portion of snout) (Figs. 18, 32, 60) . . 59 34 (33). Mouth 26 (20). Pigmentation on lateral surfaces of a. peritoneum terminal (above bottom-of-eye level) (Fig. 87) a. absent (Figs. 88, 89) X. texanus X. texanus b. low terminal (at or below bottom-of-eye b. sparse or patchy (Figs. 32, 33, 75) 27 level) to slightly c. uniformly light to dark (Fig. 47) subterminal (mouth, C. discobolus including upper lip, not the most anterior portion of snout) (Figs. 19, 89) . . . . 68 27 (26). Pigmentation on ventro-lateral surfaces of peritoneum 35 (33). Pigmentation on ventro-lateral surfaces a. absent or sparse to patchy (Figs. 32, of peritoneum 33) C commersoni a. absent (Fig. 18) 36 b. uniformly light (Fig. 75) . . C. platyrhynchus b. sparse or patchy (Fig. 33) 37 c. uniformly light to dark (Fig. 75) 28 (1). Gut (Fig. 5) with C platyrhynchus a. at least 90° bend or partial s-shaped loop (gut phase 2) C. latipinnis 36 (35). Mouth b. full loop (s-shape to near anterior end a. terminal (above bottom-of-eye level) of visceral cavity) but with neither limb (Fig. 87) X. texanus of loop completely across over ventral b. low terminal (at or below bottom-of-eye midline (gut phase 3) 29 level) to slightly subterminal (mouth, c. at least one limb of loop fully across including upper lip, not the most anter- ventral midline but not yet with both ior portion of snout) (Figs. 19, 33, 89) . 67 limbs across fully to opposite side (gut phase 4) 33 37 (31,35). Mouth d. both limbs of loop across midline fully a. terminal (above bottom-of-eye level) to opposite side (four segments of gut (Fig. 87) X. texanus crossing nearly perpendicular to body b. low terminal (at or below bottom-of-eye axis) or with more extensive coil level) to slightly subterminal (mouth, development (gut phase 5) . . C. discobolus including upper lip, not the most anterior portion of snout) (Figs. 33, 89) . . . . 73 29 (28). Pigmentation on lateral surfaces of peritoneum 38 (1). Gut (Fig. 5) with a. absent (Figs. 19, 60, 89) 30 a. at least 90° bend or partial s-shaped b. sparse or patchy (Figs. 18, 33, 75) 31 loop (gut phase 2) C. latipinnis b. full loop (s-shape to near anterior end 30 (29). Mouth of visceral cavity) but with neither limb a. terminal (above bottom-of-eye level) of loop completely across over ventral (Fig. 87) X. texanus midline (gut phase 3) 39

75 c. at least one limb of loop fully across 47 (1). Gut (Fig. 5) with ventral midline but not yet with both a. at least 90° bend or partial s-shaped limbs across fully to opposite side (gut loop (gut phase 2) C. latipinnis phase 4) 42 b. full loop (s-shape to near anterior end d. both limbs of loop across midline fully of visceral cavity) but with neither limb to opposite side (four segments of gut of loop completely across over ventral crossing nearly perpendicular to body midline (gut phase 3) 48 axis) or with more extensive coil c. at least one limb of loop fully across development (gut phase 5) . . C. discobolus ventral midline but not yet with both limbs across fully to opposite side (gut 39 (38). Pigmentation on lateral surfaces of phase 4) 50 peritoneum d. both limbs of loop across midline fully a. absent (Figs. 61, 89) 41 to opposite side (four segments of gut b. sparse or patchy (Fig. 33) 40 crossing nearly perpendicular to body axis) or with more extensive coil 40 (39). Pigmentation on ventro-lateral surfaces development (gut phase 5) . . C. discobolus of peritoneum a. absent (Figs. 61, 89) 41 48 (47). Pigmentation on lateral surfaces of b. sparse or patchy (Fig. 33) X. texanus peritoneum a. absent (Figs. 61, 89) 57 41 (39,40). Mouth b. sparse or patchy (Fig. 33) 49 a. terminal (above bottom-of-eye level) (Fig. 87) X. texanus 49 (48). Pigmentation on ventro-lateral surfaces b. low terminal (at or below bottom-of-eye of peritoneum level) to slightly subterminal (mouth, a. absent (Figs. 61, 89) 57 including upper lip, not the most anter- b. sparse or patchy (Fig. 33) X. texanus ior portion of snout) (Figs. 61, 89) . . . . 74 50 (47). Pigmentation on lateral surfaces of 42 (38). Pigmentation on lateral surfaces of peritoneum peritoneum a. absent (Figs. 61, 89) 57 a. absent (Fig. 89) X. texanus b. sparse or patchy (Fig. 75) 51 b. sparse or patchy (Fig. 75) 43 c. uniformly light to dark (Fig. 76) c. uniformly light ...... C. platyrhynchus C. platyrhynchus d. uniformly dark (Fig. 47) 44 51 (50). Pigmentation on ventro-lateral surfaces 43 (42). Pigmentation on ventro-lateral surfaces of peritoneum of peritoneum a. absent (Figs. 61,89) 57 a. absent or sparse to patchy (Fig. 89) b. sparse or patchy (Fig. 33) X. texanus X. texanus c. uniformly dark (Fig. 76) . . C. platyrhynchus b. uniformly light to dark (Fig. 76) C platyrhynchus 52 (1). Gut (Fig. 5) with a. at least 90° bend or partial s-shaped 44 (42). Pigmentation on ventro-lateral surfaces loop (gut phase 2) C. latzpinnis of peritoneum b. full loop (s-shape to near anterior end a. uniformly light ...... C. platyrhynchus of visceral cavity) but with neither limb b. uniformly dark (Fig. 76) 45 of loop completely across over ventral midline (gut phase 3) or gut with at 45 (44). Pigmentation on ventral surface of least one limb of loop fully across peritoneum ventral midline but not yet with both a. absent C platyrhynchus limbs across fully to opposite side (gut b. sparse or patchy (Fig. 75) 46 phase 4) 54 c. uniformly light to dark (Fig. 47) c. both limbs of loop across midline fully C. discobolus to opposite side (four segments of gut crossing nearly perpendicular to body 46 (45). Mouth axis) or with more extensive coil a. terminal (above bottom-of-eye level) or development (gut phase 5) . . C. discobolus low terminal (at or below bottom-of-eye level) to slightly subterminal (mouth, 53 (1). Gut (Fig. 5) with including upper lip, not the most anter- a. at least 90° bend or partial s-shaped ior portion of snout) (Fig. 75) loop (gut phase 2) C. latzpinnis C platyrhynchus b. full loop (s-shape to near anterior end b. distinctly subterminal (mouth notably of visceral cavity) but with neither limb posterior to most anterior portion of of loop completely across over ventral snout) (Fig. 47) C. discobolus midline (gut phase 3) or gut with at

76 least one limb of loop fully across ventral air bladder, visceral cavity (peri- midline but not yet with both limbs across toneum), or gut, fully to opposite side (gut phase 4) 54 a. with 1-5 melanophores C. latipinnis b. with melanophores (Figs. 18, 60) . . . 64 54 (52,53). Pigmentation on lateral surfaces of peritoneum 64 (63). Lateral surface of body below hori- a. absent (Fig. 89) X. texanus zontal myosepta (or lateral midline), b. sparse or patchy (Fig. 33) 55 exclusive of melanophores associated with horizontal myosepta, air 55 (54). Pigmentation on ventro-lateral surfaces bladder, visceral cavity (peri- of peritoneum toneum), or gut, a. absent (Figs. 61, 89) 57 a. unpigmented (Figs. 59) C. latipinnis b. sparse or patchy (Fig. 33) 56 b. with .>_.1 melanophores (Figs. 18, 60) . . 138

56 (55). Pigmentation on ventral surface of 65 (62). Lateral surface of body above hori- peritoneum zontal myosepta (or lateral midline), a. absent (Figs. 61, 89) 57 exclusive of melanophores asso- b. sparse or patchy (Fig. 75) . . . . C. latipinnis ciated with horizontal myosepta, air bladder, visceral cavity (peri- 57 (48,49,50,51,55,56). Mouth toneum), or gut, a. terminal (above bottom-of-eye level) a. unpigmented (Fig. 88) X. texanus (Fig. 87) X. texanus b. with 1-5 melanophores 91 b. low terminal (at or below bottom-of-eye c. with 6 melanophores (Figs. 18, 60, level) to slightly subterminal (mouth, 89) 66 including upper lip, not the most anterior portion of snout) (Fig. 89) . . . . 74 66 (65). Lateral surface of body below hori- c. distinctly subterminal (mouth notably zontal myosepta (or lateral midline), posterior to most anterior portion of exclusive of melanophores asso- snout) (Fig. 61) C. latipinnis ciated with horizontal myosepta, air bladder, visceral cavity (peri- 58 (32). Ventral midline from shortly behind toneum), or gut, heart region to near vent with a. unpigmented (Fig. 88) 91 a. L-21 melanophores in a continuous or b. with 1-5 melanophores (Fig. 89) 90 discontinuous line or narrow band (Fig. c. with ?_-6 melanophores (Figs. 18, 60) . . 138 32) C commersoni b. 7-20 melanophores (Fig. 17) 61 67 (3,5,16,36). Ventral midline from shortly c. melanophores (Figs. 19, 60, 89) . . . 62 behind heart region to near vent with 59 (25). Ventral midline from shortly behind a. ?._-21 melanophores in a continuous or heart region to near vent with discontinuous line or narrow band (Fig. a. -21 melanophores in a continuous or 32) C commersoni discontinuous line or narrow band (Fig. b. 7-20 melanophores (Fig. 17) . . . . C. ardens 32) C. commersoni c. melanophores (Figs. 19, 89) 69 b. melanophores (Figs. 17, 19, 60) . . . 61 68 (23,34). Ventral midline from shortly behind 60 (23,30). Ventral midline from shortly behind heart region to near vent with heart region to near vent with a. 7-20 melanophores (Fig. 17) . . . . C. ardens a. 7-20 melanophores (Fig. 17) 61 b. melanophores (Figs. 19, 89) 69 b. ..45 melanophores (Figs. 19, 60, 89) . . . 62 69 (67,68). Number of principal dorsal fin rays 61(21,58,59,60). Number of principal dorsal fin a. 10-11 C. ardens rays b. 12-14 70 a. 10 C ardens c. 15-16 X. teranus b. 11-14 63 70 (69). Lateral surface of body above hori- 62 (58,60). Number of principal dorsal fin rays zontal myosepta (or lateral midline), a. 10 C. ardens exclusive of melanophores asso- b. 11 63 ciated with horizontal myosepta, air c. 12-14 65 bladder, visceral cavity (peri- d. 15-16 X. texanus toneum), or gut, a. with melanophores (Fig. 88) X. texanus 63 (60,61,62). Lateral surface of body above b. with 2:6 melanophores (Figs. 19, 89) . . . 71 horizontal myosepta (or lateral midline), exclusive of melanophores 71 (70). Lateral surface of body below associated with horizontal myosepta, horizontal myosepta (or lateral

77 midline), exclusive of melanphores 80 (79). Lateral surface of body below hori- assciated with horizontal myosepta, zontal myosepta (or lateral midline), air bladder, visceral cavity (peri- exclusive of melanophores asso- toneum), or gut, ciated with horizontal myosepta, air a. unpigmented (Fig. 88) X. texanus bladder, visceral cavity (peri- b. with 1-5 melanophores (Fig. 89) 139 toneum), or gut, C. with 6 melanophores (Fig. 19) . C. ardens a. unpigmented C. platyrhynchus b. with 1-5 melanophores (Fig. 45) 94 72 (3,14,15,17). Ventral midline from shortly behind heart region to near vent 81 (8,12). Ventral midline from shortly behind with heart region to near vent with a. ?.._21 melanophores in a continuous or a. L-21 melanophores in a continuous or discontinuous line or narrow band (Fig. discontinuous line or narrow band (Figs. 32) C commersoni 32, 75) 82 b. - -20 melanophores (Figs. 17, 18, 19) b. 7-20 melanophores (Fig. 47) 89 C ardens c. melanophores C. discobolus

73 (10,37). Ventral midline from shortly behind 82 (81). Number of principal dorsal fin rays heart region to near vent with a. 9 89 a. ?_21 melanophores in a continuous or b. 10-12 83 discontinuous line or narrow band (Fig. C. 13 C commersoni 32) C commersoni b. melanophores (Fig. 89) . . X. texanus 83 (82). Lateral surface of body below horizontal myosepta (or lateral midline), exclusive of 74 (41,57). Ventral midline from shortly behind melanophores asso- heart region to near vent with ciated with horizontal myosepta, air a. 7-20 melanophores (Fig. 17) . . C. latipinnis bladder, visceral cavity (peritoneum), b. melanophores (Figs. 60, 89) 75 or gut, a. with melanophores (Fig. 45) 87 b. with ?_.-6 melanophores (Figs. 32, 46, Number of principal dorsal fin rays 75 (74). 74) 84 a. 11 C. latipinnis 12-14 76 b. 84 (83). Mid-lateral surface of body with c. 15-16 X. texanus a. no large, distinct spots (Figs. 32, 46, 74) ...... 97 76 (75). Lateral surface of body above hori- b. 3 large, distinct spots, one between head zontal myosepta (or lateral midline), and dorsal fm, the second over the exclusive of melanophores associated pelvic fin, and the last on the caudal with horizontal myosepta, air peduncle near the base of the tail (Fig. bladder, visceral cavity (peri- 35) C. commersoni toneum), or gut, a. unpigmented (Fig. 88) X. texanus 85 (6,8,18). Ventral midline from shortly behind b. with 1-5 melanophores 91 heart region to near vent with c. with >6 melanophores (Figs. 60, 89) 77 a. melanophores in a continuous or discontinuous line or narrow band (Fig. 77 (76). Lateral surface of body below hori- 32) ...... 86 zontal myosepta (or lateral midline), b. 7-20 melanophores (Fig. 47) exclusive of melanophores associated C. platyrhynchus with horizontal myosepta, air bladder, visceral cavity (peri- 86 (78,85). Number of principal dorsal fin rays toneum), or gut, a. 9 C. platyrhynchus a. with melanophores (Fig. 88) 91 b. 10-12 87 b. with ..15 melanophores (Fig. 60) C. latipinnis c. 13 C. commersoni

78 (6). Ventral midline from shortly behind 87 (83,86). Mid-lateral surface of body with heart region to near vent with a. no large, distinct spots (Figs. 33, 75) . . 104 a. L-21 melanophores in a continuous or b. 3 large, distinct spots, one between head discontinuous line or narrow band (Figs. and dorsal fin, the second over the 32, 75) 86 pelvic fm, and the last on the caudal b. 7-20 melanophores (Fig. 17) 79 peduncle near the base of the tail (Fig. c. melanophores (Fig. 19) C. ardens 35) C. commersoni

79 (78). Number of principal dorsal fin rays 88 (12). Ventral midline from shortly behind a. 9 C. platyrhynchus heart region to near vent with b. 10-12 80 a. melanophores (Figs. 46, 74) 89 c. 13-14 C ardens b. melanophores C. discobolus

78 89 (81,82,88). Lateral surface of body below 100 (98). Dorsal fin length horizontal myosepta (or lateral mid- a. 15-16% SL C. commersoni line), exclusive of melanophores b. 17-21% SL 129 associated with horizontal myosepta, c. 22% SL C. commersoni air bladder, visceral cavity (peritoneum), or gut, 101 (89). Longitudinal eye diameter a. with melanophores (Fig. 45) a. 22-24% of head length ...... C. discobolus C. platyrhynchus b. 25-27% of head length ...... 102 b. with 1-6 melanophores (Figs. 46, 74) .. 101 c. 28% of head length C platyrhynchus

90 (66). Longitudinal eye diameter 102 (101). Length of base of dorsal fin (origin to a. 22-23% of head length ...... C. latipinnis insertion of dorsal fin) b. 24-25% of head length ...... 92 a. 11-14% SL 103 c. 26-27% of head length X texanus b. 15% SL C. discobolus d. 28-32% of head length ...... 139 e. 33% of head length C ardens 103 (98,102). Dorsal fin length a. 15-16% SL C. platyrhynchus 91 (65,66,76,77). Longitudinal eye diameter b. 17-19% SL 114 a. 22-23% of head length ...... C. latipinnis c. 20-21% SL C. discobolus b. 24-25% of head length ...... 92 c. 26-32% of head length ...... X. texanus 104 (87). Longitudinal eye diameter a. 25-28% of head length ...... 105 92 (90,91). Length of base of dorsal fin (origin b. 29-34% of head length . . . . C. commersoni to insertion of dorsal fm) a. 14-15% SL C. latipinnis 105(97,104). Length of base of dorsal fin (origin b. 16-17% SL 93 to insertion of dorsal fin) c. 18-21% SL X. texanus a. 11% SL C. platyrhynchus b. 12-14% SL 106 93 (92). Dorsal fin length c. 15% SL C. commersoni a. 20% SL C. latipinnis b. 21-24% SL 107 106 (105). Dorsal fin length c. 25-29% SL X. texanus a. 15-19% SL 123 b. 20-22% SL C. commersoni 94 (80). Longitudinal eye diameter a. 25-27% of head length . . . C. platyrhynchus 107 (93). Caudal fin length (total length minus b. 28% of head length ...... 95 standard length) c. 29-33% of head length C ardens a. 17-19% SL C. latipinnis b. 20-26% SL C. latipinnis 95 (94). Length of base of dorsal fin (origin to X. texanus insertion of dorsal fin) c. 27-28% SL X. texanus a. 11-13% SL C plalyrhynchus 108 (96). Pigment over ventral to ventro-lateral b. 14% SL 96 surfaces of gill covers (opercula) c. 15-16% SL C. ardens a. absent or present but not in distinct oblique rows of 3 or more melanophores 96(95). Dorsal fin length near or along ventral margin of either a. 15-17% SL C platyrhynchus preopercle (Figs. 19,75) 109 b. 18-19% SL 108 b. present in a distinct oblique row of 3 or C. 20% SL C ardens more melanophores near or along ventral margin of one or both preopercles 97(84). Longitudinal eye diameter (Fig. 74) C. platyrhynchus a. 22-24% of head length ...... C. discobolus b. 25-27% of head length ...... 98 109 (108). Pigment in anal fin C. 28% of head length ...... 105 a. absent or present but very light with d. 29-34% of head length .. . . C. commersoni only a few (-_5) melanophores (Figs 19,75) 110 98 (97). Length of base of dorsal fin (origin to b. present but more prominent with many insertion of dorsal fin) (?..15) melanophores C. ardens a. 11% SL 103 b. 12-14% SL 99 110 (109). Number of myomeres to posterior c. 15% SL 100 margin of vent a. 32-33 C. platyrhynchus 99 (98). Dorsal fin length b. 34-37 111 a. 15-16% SL 123 c. 38 C ardens b. 17-19% SL 115 c. 20-21% SL 129 111 (110). Total number of myomeres d. 22% SL C commersoni a. 43-47 112

79 b. 48 G ardens 121 (120). Number of myomeres to posterior margin of vent 112 (111). Caudal fin length (total length minus a. 32-33 C platyrhynchus standard length) b. 34 125 a. 15-17% SL C. platyrhynchus c. 35-37 122 b. 18-20% SL 1L3 d. 38-40 133 c. 21-22% SL C. ardens 122 (121). Total number of myomeres 113 (112). Length from anterior margin of snout a. 43-47 C commersoni to insertion of dorsal fin C. platyrhynchus a. 62-63% SL C platyrhynchus b. 47-48 C commersoni b. 64-65% SL C. ardens C. discobolus C. platyrhynchus C. platyrhynchus c. 66-67% SL C. ardens c. 47-48 C commersoni C. discobolus 114 (103). Pigment over ventral to ventro-lateral surfaces of gill covers (opercula) 123 (99,106,115). Pigment on ventral surface of a. absent or present but not in a distinct heart region oblique row of 3 or more melanophores a. absent ...... C. platyrhynchus near or along ventral margin of one or b. present (Figs. 32, 74, 75) 124 both preopercles (Figs. 47, 75) 117 b. present in a distinct oblique row of 3 or 124 (120,123). Number of myomeres to poster- more melanophores near or along ven- ior margin of vent tral margin of one or both preopercles a. 32-33 C platyrhynchus (Fig. 74) C platyrhynchus b. 34-37 125 c. 38-40 C. commersoni 115 (99). Pigment over ventral to ventro-lateral surfaces of gill covers (opercula) 125 (121,124). Total number of myomeres a. absent or present but not in a distinct a. 43-47 126 oblique row of 3 or more melanophores b. 48-49 C. commersoni near or along ventral margin of one or both preopercles (Figs. 32, 47, 75) . . . 116 126 (125). Pigment in dorsal fm b. present in a distinct oblique row of 3 or a. along fm rays with very few, if any, more melanophores near or along ven- melanophores on membrane between tral margin of one or both preopercles rays (Fig. 75) 127 (Figs. 31, 74) 123 b. abundant both along and between rays (Fig. 33) C. commersoni 116 (115). Pigment on ventral surface of heart region 127 (126). Pigment in anal fin a. absent (Fig. 47) 117 a. absent or present but very light with b. present (Figs. 32, 46, 74) 120 only a few (- 5) melanophores 128 b. present but more prominent with many 117 (114,116). Pigment in pectoral fin (L-6) melanophores C. commersoni a. absent or present but very light with melanophores (Fig. 47) 118 128 (127). Caudal fin length (total length minus b. present but more prominent with L-11 standard length) melanophores (Fig. 75) . . C. platyrhynchus a. 15% SL C. platyrhynchus b. 16-20% SL C. commersoni 118 (117). Number of myomeres to posterior C. platyrhynchus margin of vent c. 121-126% SL C commersoni a. 32-34 C. platyrhynchus b. 35-37 119 129 (99,100). Pigment over ventral to ventro- c. 38-40 C. discobolus lateral surfaces of gill covers (opercula) 119 (118). Total number of myomeres a. absent or present but not in a distinct a. 43-46 C platyrhynchus oblique row of 3 or more melanophores b. 48-49 C. discobolus near or along ventral margin of one or C platyrhynchus both preopercles (Figs. 32, 46) 130 c. 48-49 C. discobolus b. present in a distinct oblique row of 3 or more melanophores near or along ven- 120 (116). Pigment in pectoral fin tral margin of one or both preopercles a. absent or present but very light with (Fig. 31) C commersoni melanophores (Fig. 47) 121 b. present but more prominent with 11 130 (129). Pigment on ventral surface of heart melanophores (Fig. 75) 124 region

80 a. absent (Fig. 47) C. discobolus a. 18-20% SL C. ardens b. present (Figs. 32, 46) 131 b. 21-29% SL ...... X. texanus

131 (130). Pigment in pectoral fm a. absent or present but very light with :510 Skeletal Character Key for Metalarvae that melanophores (Fig. 47) 132 have been cleared and preferably stained b. present but more prominent with a-11 for bone or cartilage (Fig. 6). melanophores (Fig. 61) . . . C. commersoni 1. Standard length group (Fig. 4) 132 (131). Number of myomeres to posterior a. mm 2 margin of vent b. 17-18 mm 3 a. 34 C commersoni c. 19-21 mm 5 b. 35-40 133 d. a22 mm 9

133 (121,132). Total number of myomeres 2 (1). Number of vertebrae (including 4 for a. 43-46 C commersoni Weberian complex) b. 47-49 134 a. 42-43 C. platyrhynchus b. 44 C. commersoni 134 (133). Dorsal body pigmentation between C. platyrhynchus head and last myomere scattered c. 45-46 C commersoni a. more or less evenly (with or without C. discobolus emphasis on distinct lines of melano- C. platyrhynchus phores on or lateral and parallel to X. texanus dorsal midline) (Fig. 47) 135 d. 47 C. ardens b. but in a blotchy pattern (with or without C. commersoni emphasis on distinct lines of melano- C. discobolus phores on or lateral and parallel to C. platyrhynchus dorsal midline) (Fig. 48, 49) . C. discobolus X. texanus e. 48 C ardens 135 (134). Pigment in dorsal fin C. commersoni a. along fm rays with very few, if any, C. discobolus melanophores on membrane between C. platyrhynchus rays (Fig. 47) 136 f. 49-50 C. discobolus b. abundant both along and between rays (rarely) C. platyrhynchus (Fig. 33) C commersoni 3 (1). First (most anterior) interneural bone 136 (135). Pigment in anal fm (Fig. 8) a. absent or fin present but very light with a. large and fan-shaped across top X. texanus only a few (- 5) melanophores (Fig b. large and angular or anvil-shaped with 47) 137 a prominent posterior-directed projec- b. present but more prominent with many tion or bealc 4 (a6) melanophores (Fig. 61) C. commersoni c. small and blocky or angular with a small to moderate posterior-directed projec- 137 (136). Length from anterior margin of snout tion or beak ...... 11 to origin of pelvic fin a. 54% SL C commersoni 4 (3). Number of vertebrae (including 4 for b. 55-59% SL C commersoni a. 44_46Weberian complex) C. discobolus C commersoni c. 60-61% SL C. discobolus b. 47-48 C ardens C. commersoni 138 (64,66). Longitudinal eye diameter a. 22-25% of head length ...... C. latipinnis 5 (1). Frontoparietal fontanelle (Fig. 7) b. 28-33% of head length ...... C. ardens a. wide, - 54% of fontanelle length ...... 6 b. very wide, 55-64% of fontanelle length 139 (71,90). Longitudinal eye diameter (often somewhat oval in shape) ...... 8 a. 24-27% of head length . Xyrauchen tetanus c. very wide, a65% of fontanelle length b. 28-32% of head length ...... 140 (often somewhat oval in shape) X. texanus c. 33% of head length C ardens 6 (5). First (most anterior) interneural bone 140 (139). Length of base of dorsal fin (origin to (Fig. 8) insertion of dorsal fin) a. large and angular or anvil-shaped with a. 14-15% SL C. ardens a prominent posterior-directed projec- b. 16% SL 141 tion or beak ...... 7 c. 17-21% SL X. texanus b. small and blocky or angular with a small to moderate posterior-directed projec- 141 (140). Dorsal fin length tion or beak ...... 11

81 7 (6). Number of vertebrae (including 4 for 10 (9). First (most anterior) interneural bone Weberian complex) (Fig. 8) a. 44-46 C commersoni a. large and angular or anvil-shaped with b. 47-48 C ardens a prominent posterior-directed projec- C. commersoni tion or beak; anterior ends of mandibles C. latipinnis (from ventral view of head) well anter- c. 49-50 C. latipinnis ior, at least mid-distance between posterior and anterior ends of maxillae; anterior-dorsal maxillary projections 8 (5). First (most anterior) interneural bone small and rounded to reduced and (Fig. 8) almost absent ...... C. latipinnis a. large and fan-shaped across top X. texanus b. small and blocky or angular with a small b. large and angular or anvil-shaped with a to moderate posterior-directed projec- prominent posterior-directed projection tion or beak; anterior ends of mandibles or beak ...... C. latipinnis (from ventral view of head) well posterior, much closer to posterior than anter- 9 (1). Frontoparietal fontanelle (Fig. 7) ior ends of maxillae; anterior-dorsal a. narrow, 0% of fontanelle length . . 11 maxillary projections prominent and b. moderately wide, 31-40% of fontanelle pointed ...... 11 length ...... 10 c. wide, 41-47% of fontanelle length 11(3,6,9,10). Number of vertebrae (including 4 ...... C. lattpinnis for Weberian complex) d. very wide, .-48% of fontanelle length a. 42-44 C. platyrhynchus (often over 60% and somewhat oval in b. 45-50 C. discobolus shape) ...... X. texanus (rarely) C. platyrhynchus

Juveniles :540 mm SL -- no finfold remaining 3 (1). Gut (Fig. 5) with (Figs. 20, 21; definition abbreviated for a. full loop (s-shape to near anterior end species of concern; there may be rare of visceral cavity) but with neither limb metalarval specimens in which all finfold of loop completely across over ventral is lost but not all pelvic fin rays or rudi- midline (gut phase 3) or gut with at least one limb of loop fully across mentary caudal fin rays are yet present). ventral midline but not yet with both Separate skeletal character key at end for limbs across fully to opposite side (gut confirmation of identity or further diag- phase 4) 4 nosis of specimens cleared (and preferably b. both limbs of loop across midline fully stained) for bone. to opposite side (four segments of gut crossing nearly perpendicular to body 1. Standard length (SL; Fig. 4) axis) or with more extensive coil devel- a. 17-18 mm C commersoni opment (gut phase 5) C. commersoni b. 19 mm 2 c. 20 mm 3 4(2,3). Mouth d. 21 mm 5 a. low terminal (at or below bottom-of-eye e. 22 mm 10 level) to slightly subterminal (mouth, f. 23-25 mm 23 including upper lip, not the most anter- g. 26-28 mm ao ior portion of snout) (Figs. 20, 34) . 104 h. 29-31 mm 58 b. distinctly subterminal (mouth notably i. 32-34 mm 71 posterior to most anterior portion of j. 35-37 mm 76 snout) (Fig. 63) C commersoni k. 38-40 mm 85 5 (1). Gut (Fig. 5) with 2 (1). Gut (Fig. 5) with a. full loop (s-shape to near anterior end a. at least 90° bend or partial s-shaped loop of visceral cavity) but with neither limb (gut phase 2) C ardens of loop completely across over ventral b. full loop (s-shape to near anterior end midline (gut phase 3) 7 of visceral cavity) but with neither limb b. at least one limb of loop fully across of loop completely across over ventral ventral midline but not yet with both midline (gut phase 3) 4 limbs across fully to opposite side (gut c. at least one limb of loop fully across phase 4) 6 ventral midline but not yet with both c. both limbs of loop across midline fully limbs across fully to opposite side (gut to opposite side (four segments of gut phase 4) C commersoni crossing nearly perpendicular to body

82 axis) or with more extensive coil 14 (13). Pigmentation on ventral surface of development (gut phase 5) 9 peritoneum a. absent (Figs. 20, 34) 15 6 (5). Pigmentation on ventro-lateral surfaces of b. sparse or patchy (Fig. 63) . . C. commersoni peritoneum a. absent, obstructed from view by muscle, 15 (14). Mouth sparse, or patchy (Figs. 20, 34, 90) 7 a. terminal (above bottom-of-eye level) b. uniformly dark (Fig. 76) . . C. platyrhynchus ...... X. teranus b. low terminal (at or below bottom-of-eye 7 (5,6). Mouth level) to slightly subterminal (mouth, a. terminal (above bottom-of-eye level) including upper lip, not the most anter- ...... X. texanus ior portion of snout) (Figs. 20, 34) . . . . 16 b. low terminal (at or below bottom-of-eye C. distinctly subterminal (mouth notably level) to slightly subterminal (mouth, posterior to most anterior portion of including upper lip, not the most anter- snout) (Fig. 63) C. commersoni ior portion of snout) (Figs. 20, 24, 90) . . . 8 c. distinctly subterminal (mouth notably 16(15). Scales posterior to most anterior portion of a. not apparent (Figs. 20, 34, 90) 100 snout) (Fig. 63) C commersoni b. present but lateral series incomplete or uncountable ...... 104 8 (7). Scales a. not apparent (Figs. 20, 34, 90) 100 17 (10). Pigmentation on ventro-lateral surfaces b. present but lateral series incomplete or of peritoneum uncountable ...... C. ardens a. absent, obstructed from view by muscle, sparse, or patchy (Figs. 34, 90) 18 9 (5). Pigmentation on ventro-lateral surfaces of b. uniformly dark (Figs. 48, 76) 21 peritoneum a. absent, obstructed from view by muscle, 18 (17) . Pigmentation on ventral surface of sparse, or patchy (Fig. 34) . C. commersoni peritoneum b. uniformly dark (Figs. 48, 76) 21 a. absent (Figs. 34, 90) 19 b. sparse or patchy (Figs. 63) . C. commersoni 10 (I). Gut (Fig. 5) with a. full loop (s-shape to near anterior end of 19 (18). Mouth visceral cavity) but with neither limb of a. terminal (above bottom-of-eye level) loop completely across over ventral mid- ...... X. texanus line (gut phase 3) 11 b. low terminal (at or below bottom-of-eye b. at least one limb of loop fully across level) to slightly subterminal (mouth, ventral midline but not yet with both including upper lip, not the most anter- limbs across fully to opposite side (gut ior portion of snout) (Figs. 34, 90) . . . . 20 phase 4) 13 c. distinctly subterminal (mouth notably c. both limbs of loop across midline fully posterior to most anterior portion of to opposite side (four segments of gut snout) (Fig. 63) C commersoni crossing nearly perpendicular to body axis) or with more extensive coil devel- 20 (19). Scales opment (gut phase 5) 17 a. not apparent (Figs. 34, 90) 108 b. present but lateral series incomplete or 11(10). Mouth uncountable C commersoni a. terminal (above bottom-of-eye level) ...... X. texanus 21 (9,17). Pigmentation on ventral surface of b. low terminal (at or below bottom-of-eye peritoneum level) to slightly subterminal (mouth, a. sparse or patchy (Figs. 48, 76) 22 including upper lip, not the most anter- b. uniformly light or dark (Fig. 49) ior portion of snout) (Figs. 20, 90) . . . . 12 C. discobolus

12 (11). Scales 22 (21). Mouth a. not apparent (Figs. 20, 90) 111 a. terminal (above bottom-of-eye level) or b. present but lateral series incomplete or low terminal (at or below bottom-of-eye uncountable C ardens level) to slightly subterminal (mouth, including upper lip, not the most anter- 13 (10). Pigmentation on ventro-lateral surfaces ior portion of snout) (Fig. 75) of peritoneum C. platyrhynchus a. absent, obstructed from view by muscle, b. distinctly subterminal (mouth notably sparse, or patchy (Figs. 20, 34) 14 posterior to most anterior portion of b. uniformly dark (Fig. 76) . . C. platyrhynchus snout) (Figs. 48, 76) C. discobolus

83 23 (1). Gut (Fig. 5) with b. present but lateral series incomplete or a. at least 90° bend or partial s-shaped loop uncountable 104 (gut phase 2) C. latipinnis c. present with lateral series complete and b. full loop (s-shape to near anterior end countable (Fig. 21) C. ardens of visceral cavity) but with neither limb of loop completely across over ventral 31 (27). Mouth midline (gut phase 3) 24 a. terminal (above bottom-of-eye level) c. at least one limb of loop fully across ...... X. tetanus ventral midline but not yet with both b. low terminal (at or below bottom-of-eye limbs across fully to opposite side (gut level) to slightly subterminal (mouth, phase 4) 26 including upper lip, not the most anter- d. both limbs of loop across midline fully to ior portion of snout) (Figs. 34, 62, 90) 32 opposite side (four segments of gut c. distinctly subterminal (mouth notably crossing nearly perpendicular to body posterior to most anterior portion of axis) or with more extensive coil snout) (Fig. 63) 33 development (gut phase 5) 34 32 (31). Scales 24 (23). Mouth a. not apparent (Figs. 34, 62, 90) ...... 105 a. terminal (above bottom-of-eye level) ...... b. present but lateral series incomplete or ...... X. texanus uncountable 107 b. low terminal (at or below bottom-of-eye level) to slightly subterminal (mouth, 33 (31). Scales including upper lip, not the most anter- a. not apparent (Figs. 34, 62) ...... 113 ior portion of snout) (Figs. 62, 90) . . . 25 b. present but lateral series incomplete or c. distinctly subterminal (mouth notably uncountable C commersoni posterior to most anterior portion of snout) (Fig. 63) C. latipinnis 34(23). Pigmentation on ventro-lateral surfaces of peritoneum 25 (24). Scales a. a. not apparent (Figs. 62, 90) 115 absent, obstructed from view by muscle, b. present but lateral series incomplete or sparse, or patchy (Figs. 34, 90) 35 b. uniformly dark (Figs. uncountable ...... X. tetanus 48, 76) 37

26 (23). Pigmentation on ventro-lateral surfaces 35(34). Mouth of peritoneum a. terminal (above bottom-of-eye level) a. absent, obstructed from view by muscle, ...... X. texanus sparse, or patchy (Figs. 20, 34, 62, 90) . . 27 b. low terminal (at or below bottom-of-eye b. uniformly dark (Fig. 76) . . C. platyrhynchus level) to slightly subterminal (mouth, including upper lip, not the most anter- 27 (26). Pigmentation on ventral surface of ior portion of snout) (Figs. 34, 90) . . . . 36 peritoneum c. distinctly subterminal (mouth notably a. absent (Figs. 20, 34, 62, 90) 28 posterior to most anterior portion of b. sparse or patchy (Fig. 63) 31 snout) (Fig. 63) C commersoni

28 (27). Mouth 36(35). Scales a. terminal (above bottom-of-eye level) a. not apparent (Figs. 34, 90) 108 ...... X. tetanus b. present but lateral series incomplete or b. low terminal (at or below bottom-of-eye uncountable ...... 107 level) to slightly subterminal (mouth, including upper lip, not the most anter- 37 (34). Pigmentation on ventral surface of ior portion of snout) (Figs. 20, 34, 62, peritoneum 90) 29 a. sparse or patchy (Figs. 48, 76) ...... 38 c. distinctly subterminal (mouth notably b. uniformly light or dark (Fig. 49) posterior to most anterior portion of C. discobolus snout) (Fig. 63) 30 38(37). Mouth 29 (28). Scales a. terminal (above bottom-of-eye level) or a. not apparent (Figs. 20, 34, 62, 90) 97 low terminal (at or below bottom-of-eye b. present but lateral series incomplete or level) to slightly subterminal (mouth, uncountable ...... 99 including upper lip, not the most anter- c. present with lateral series complete and ior portion of snout) (Fig. 75) countable (Fig. 21) C. ardens C. platyrhynchus b. distinctly subterminal (mouth notably 30 (28). Scales posterior to most anterior portion of a. not apparent (Figs. 20, 34, 62) 102 snout) (Figs. 48, 76) 39

84 b. distinctly subterminal (mouth notably 39 (38). Scales ...... a. not apparent (Figs. 48, 76) ...... 182 posterior to most anterior portion of b. present but lateral series incomplete or snout) (Fig. 63) ...... C. latipinnis uncountable ...... C. platyrhynchus 48(47). Scales a. not apparent (Figs. 62, 90) ...... 115 Gut (Fig. 5)0 with at least 90 bend or partial s-shaped loop b. present but lateral series incomplete or (gut phase 2) ...... C. latipinnis uncountable ...... X. tetanus full loop (s-shape to near anterior end of visceral cavity) but with neither limb of 49 (40). Pigmentation on ventro-lateral surfaces loop completely across over ventral mid- of peritoneum line (gut phase 3) ...... 41 a. absent, obstructed from view by muscle, at least one limb of loop fully across sparse, or patchy, lips at corners of ventral midline but not yet with both mouth joined, not separated by distinct limbs across fully to opposite side (gut notches (Figs. 20, 34, 90) ...... 50 phase 4) ...... 42 b. uniformly light; lips at corners of mouth both limbs of loop across midline fully to joined, not separated by distinct opposite side (four segments of gut notches ...... X. tetanus crossing nearly perpendicular to body c. uniformly dark; lips at corners of mouth axis) or with more extensive coil devel- separated by distinct notches (Figs. 48, opment (gut phase 5) ...... 49 76) ...... 56

41(40). Pigmentation on ventro-lateral surfaces 50 (49). Pigmentation on ventral surface of of peritoneum peritoneum a. absent, obstructed from view by muscle, a. absent (Figs. 20, 34, 90) ...... 51 sparse, or patchy (Figs. 62, 90) ...... 47 b. sparse or patchy (Fig. 63) ...... 54 b. uniformly light ...... X. tetanus 51(50). Mouth 42 (40). Pigmentation on ventro-lateral surfaces a. low terminal (at or below bottom-of-eye of peritoneum level) to slightly subterminal (mouth, a. absent, obstructed from view by muscle, including upper lip, not the most anter- sparse, or patchy (Figs. 20, 62, 90) . . . . 43 ior portion of snout) (Figs. 20, 34, 90) . 52 b. uniformly light ...... X. tetanus b. distinctly subterminal (mouth notably posterior to most anterior portion of snout) (Fig. 63) ...... 53 43 (42). Pigmentation on ventral surface of peritoneum 52 (51). Scales a. absent (Figs. 20, 62, 90) ...... 44 a. not apparent (Fig. 90) ...... X. tetanus sparse or patchy (Fig. 63) ...... 47 b. b. present but lateral series incomplete or uncountable ...... 99 44 (43). Mouth C. present with lateral series complete and a. low terminal (at or below bottom-of-eye countable (Fig. 21) ...... C. ardens level) to slightly subterminal (mouth, including upper lip, not the most anter- 53 (51). Scales ior portion of snout) (Figs. 20, 62, 90) . . 45 a. present but lateral series incomplete or b. distinctly subterminal (mouth notably uncountable ...... 104 posterior to most anterior portion of b. present with lateral series complete and snout) (Fig. 63) ...... 46 countable (Fig. 21) C ardens

45 (44). Scales 54(50). Mouth a. not apparent (Figs. 62, 90) ...... 115 a. low terminal (at or below bottom-of-eye b. present but lateral series incomplete or level) to slightly subterminal (mouth, uncountable ...... 110 including upper lip, not the most anter- c. present with lateral series complete and ior portion of snout) (Figs. 34, 90) . . . . 55 countable (Fig. 21) ...... C. ardens b. distinctly subterminal (mouth notably posterior to most anterior portion of 46 (44). Scales snout) (Fig. 63) C commersoni a. not apparent (Fig. 62) ...... C. latipinnis b. clearly present (Fig. 21) C ardens 55(54). Scales a. not apparent (Fig. 90) ...... X. tetanus 47 (41,43). Mouth b. present but lateral series incomplete or a. low terminal (at or below bottom-of-eye uncountable ...... 107 level) to slightly subterminal (mouth, including upper lip, not the most anter- 56 (49). Pigmentation on ventral surface of ior portion of snout) (Figs. 62, 90) . . . . 48 peritoneum

85 a. sparse, patchy, or uniformly light (Fig. b. sparse or patchy (Fig. 63) 68 76) C plalyrhynchus c. uniformly light ...... X. texanus b. uniformly dark (Fig. 49) 57 65 (64). Mouth 57 (56). Scales a. low terminal (at or below bottom-of-eye a. not apparent (Fig. 48) C. discobolus level) to slightly subterminal (mouth, b. present but lateral series incomplete or including upper lip, not the most uncountable ...... 117 anterior portion of snout) (Figs. 21, 34, 90) 66 58 (1). Gut (Fig. 5) with b. distinctly subterminal (mouth notably a. full loop (s-shape to near anterior end of posterior to most anterior portion of visceral cavity) but with neither limb of snout) (Fig. 63) 67 loop completely across over ventral midline (gut phase 3) C. latipinnis 66 (65). Scales b. at least one limb of loop fully across a. not apparent (Fig. 62) C. latipinnis ventral midline but not yet with both b. present but lateral series incomplete or limbs across fully to opposite side (gut uncountable ...... 107 phase 4) 59 c. present with lateral series complete and c. both limbs of loop across midline fully to countable (Figs. 21, 35) 103 opposite side (four segments of gut crossing nearly perpendicular to body 67 (65). Scales axis) or with more extensive coil devel- a. not apparent (Fig. 62) C. latipinnis opment (gut phase 5) 63 b. present but lateral series incomplete or uncountable ...... C commersoni 59 (58). Pigmentation on ventro-lateral surfaces c. present with lateral series complete and of peritoneum countable (Figs. 21, 35) 103 a. absent, obstructed from view by muscle, sparse, or patchy (Figs. 62, 91) 60 68 (64). Mouth b. uniformly light ...... X. texanus a. low terminal (at or below bottom-of-eye level) to slightly subterminal (mouth, 60 (59). Pigmentation on ventral surface of including upper lip, not the most anter- peritoneum ior portion of snout) (Figs. 35, 62, 90) . 69 a. absent, sparse or patchy (Figs. 62, 91) . . 61 b. distinctly subterminal (mouth notably b. uniformly light ...... X. texanus posterior to most anterior portion of snout) (Fig. 63) 70 61 (60). Mouth a. low terminal (at or below bottom-of-eye 69 (68). Scales level) to slightly subterminal (mouth, a. not apparent (Fig. 62) C. latipinnis including upper lip, not the most anter- b. present but lateral series incomplete or ior portion of snout) (Figs. 62, 91) . . . 62 uncountable ...... 107 b. distinctly subterminal (mouth notably c. present with lateral series complete and posterior to most anterior portion of countable (Fig. 35) C commersoni snout) (Fig. 63) C. latipinnis 70 (68). Scales 62 (61). Scales a. not apparent (Fig. 62) C. latipinnis a. not apparent (Fig. 62) C. latipinnis b. clearly present (Fig. 35) . . . C. commersoni b. present but lateral series incomplete or uncountable ...... X. texanus 71 (1). Gut (Fig. 5) with a. full loop (s-shape to near anterior end 63 (58). Pigmentation on ventro-lateral surfaces of visceral cavity) but with neither limb of peritoneum of loop completely across over ventral a. absent, obstructed from view by muscle, midline (gut phase 3) or gut with at sparse, or patchy; lips at corners of least one limb of loop fully across mouth joined, not separated by distinct ventral midline but not yet with both notches (Figs. 21, 35, 62, 91) 64 limbs across fully to opposite side (gut b. uniformly light; lips at corners of mouth phase 4) C. latipinnis joined, not separated by distinct b. both limbs of loop across midline fully notches ...... X. texanus to opposite side (four segments of gut c. uniformly dark; lips at corners of mouth crossing nearly perpendicular to body separated by distinct notches (Figs. 48, axis) or with more extensive coil devel- 76) 74 opment (gut phase 5) 72

64 (63). Pigmentation on ventral surface of 72 (71). Pigmentation on ventro-lateral surfaces peritoneum of peritoneum a. absent (Figs. 21, 34, 62, 91) 65 a. absent, obstructed from view by muscle,

86 sparse, or patchy; lips at corners of low terminal (at or below bottom-of-eye mouth joined, not separated by dis- level) to slightly subterminal (mouth, tinct notches (Figs. 21, 35, 63, 91) .. 73 including upper lip, not the most anter- b. uniformly light; lips at corners of mouth ior portion of snout) (Figs. 35, 91) . . 83A joined, not separated by distinct b. distinctly subterminal (mouth notably notches ...... X. texanus posterior to most anterior portion of c. uniformly dark; lips at corners of mouth snout) (Fig. 63) 81A separated by distinct notches (Figs. 49, 77) 74 80B (79). Mouth a. low terminal (at or below bottom-of-eye 73 (72). Pigmentation on ventral surface of level) to slightly subterminal (mouth, peritoneum including upper lip, not the most anter- a. absent (Figs. 21, 91) 80A ior portion of snout) (Figs. 35, 91) . . . . 83B b. sparse or patchy (Fig. 63) 83A b. distinctly subterminal (mouth notably c. uniformly light or dark (Fig. 49) X. texanus posterior to most anterior portion of snout) (Fig. 63) 81B 74 (63,72). Pigmentation on ventral surface of peritoneum 81A (80A). Scales a. sparse, patchy, or uniformly light (Fig. a. not apparent (Fig. 63) C. latipinnis 76) C platyrhynchus b. present but lateral series incomplete or b. uniformly dark (Fig. 49) 75 uncountable ...... X. texanus c. present with lateral series complete and 75 (74). Scales countable (Figs. 21, 35) 98 a. not apparent (Fig. 49) C. discobolus b. present but lateral series incomplete or 81B (80B). Scales uncountable ...... 117 a. not apparent (Fig. 63) C. latipinnis c. present with lateral series complete and b. present but lateral series incomplete or countable ...... 116 uncountable ...... 115 c. present with lateral series complete and 76 (1). Gut (Fig. 5) with countable (Figs. 21, 35) 98 a. full loop (s-shape to near anterior end of visceral cavity) but with neither limb of 82 (78). Pigmentation on ventral surface of loop completely across over ventral mid- peritoneum line (gut phase 3) or gut with at least a. absent, sparse or patchy (Figs. 35, 91) . 83B one limb of loop fully across ventral b. uniformly light ...... 84 midline but not yet with both limbs c. uniformly dark (Fig. 49) X. texanus across fully to opposite side (gut phase 4) C. latipinnis 83A (73,80A,). Scales b. both limbs of loop across midline fully to a. not apparent (Fig. 63) C. latipinnis opposite side (four segments of gut b. present but lateral series incomplete or crossing nearly perpendicular to body uncountable ...... X. texanus axis) or with more extensive coil devel- c. present with lateral series complete and opment (gut phase 5) 77 countable (Fig. 35) 106

77 (76). Lips at corners of mouth 83B (79,82). Scales a. joined, not separated by distinct notches a. not apparent (Fig. 63) C. latipinnis (Figs. 21, 35, 63, 91) 78 b. present but lateral series incomplete or b. separated by distinct notches (Figs. 49, uncountable ...... 115 77) 96 c. present with lateral series complete and countable (Fig. 35) 106 78 (77). Pigmentation on ventro-lateral surfaces of peritoneum 84 (79,82). Scales a. absent, obstructed from view by muscle, a. present but lateral series incomplete or sparse, or patchy (Figs. 21, 35, 63, 91) . . 79 uncountable ...... X. texanus b. uniformly light ...... 82 b. present with lateral series complete and c. uniformly dark ...... X. texanus countable (Fig. 35) 106

79 (78). Pigmentation on ventral surface of 85 (1). Gut (Fig. 5) with peritoneum a. at least one limb of loop fully across a. absent (Figs. 21, 91) 80B ventral midline but not yet with both b. sparse or patchy (Fig. 63) 83B limbs across fully to opposite side (gut c. uniformly light ...... 84 phase 4) C. latipinnis d. uniformly dark ...... X. texanus b. both limbs of loop across midline fully to opposite side (four segments of gut 80A (73). Mouth crossing nearly perpendicular to body

87 axis) or with more extensive coil devel- b. present with lateral series complete and opment (gut phase 5) 86 countable (Fig. 21) 109

86 (85). Lips at corners of mouth 96 (77,86). Scales a. joined, not separated by distinct notches a. present but lateral series incomplete or (Figs. 21, 35, 63, 91) 87 uncountable (Figs. 49, 77) 117 b. separated by distinct notches (Figs. 49, b. present with lateral series complete and 77)6 countable ...... 116

87 (86). Pigmentation on ventro-lateral surfaces 97 (29). Number of principal dorsal fin rays of peritoneum a. 10 137 a. absent or obstructed from view by b. 11 125 88 muscle (Figs. 21, 35, 91) c. 12-13 118 b. sparse or patchy (Fig. 63) 93 d. 14 159 c. uniformly light or dark ...... C. latipinnis e. 15-16 X. texanus

88 (87). Pigmentation on ventral surface of 98 (81A,81B). Number of lateral rows of scales peritoneum beginning with first lateral line scale a. absent (Figs. 21, 35) 89 (equals lateral line scale count if b. sparse or patchy (Fig. 63) . . . . C. latipinnis lateral line is complete and observ- c. uniformly light or dark ...... 92 able to base of caudal fin) a. 53-67 104 89 (88). Mouth b. 68-79 99 a. low terminal (at or below bottom-of-eye c. 80-85 107 level) to slightly subterminal (mouth, d. 86-95 X. texanus including upper lip, not the most anterior portion of snout) (Fig. 35) 90 99 (29,52,98). Pigment outlining scales b. distinctly subterminal (mouth notably a. absent or light (Figs. 20, 34, 91) 100 posterior to most anterior portion of b. bold (Figs. 21, 35) 104 snout) (Fig. 63) 91 100 (8,16,99). Number of principal dorsal fm 90 (89). Scales rays a. absent, incomplete, or uncountable (Fig. a. 10-11 137 63) C. latipinnis b. 12-13 130 b. present with lateral series complete and c. 14 170 countable (Fig. 35) 112 d. 15-16 X. texanus

91 (89). Scales 101 (91). Number of lateral rows of scales a. absent, incomplete, or uncountable (Fig. beginning with first lateral line scale 63) C. latipinnis (equals lateral line scale count if b. present with lateral series complete and lateral line is complete and observ- countable (Figs. 21, 35) 101 able to base of caudal fm) a. 53-79 104 92 (88). Scales b. 80-85 C commersoni a. absent, incomplete, or uncountable (Fig. c. 89-120 C. latipinnis 63) C. latipinnis b. present with lateral series complete and 102 (30). Number of principal dorsal fm rays countable ...... 114 a. 10 137 b. 11-13 125 93 (87). Pigmentation on ventral surface of c. 14 166 peritoneum a. absent (Fig. 21) 94 103 (66,67). Number of lateral rows of scales b. present (Fig. 63) C. latipinnis beginning with first lateral line scale (equals lateral line scale count if 94 (93). Mouth lateral line is complete and observ- a. low terminal (at or below bottom-of-eye able to base of caudal fin) level) to slightly subterminal (mouth, a. 53-79 104 including upper lip, not the most anter- b. 80-85 C commersoni ior portion of snout) ...... C. latipinnis b. distinctly subterminal (mouth notably 104 (4,16,30,53,98,99,101,103). Number of posterior to most anterior portion of principal dorsal fm rays snout) (Fig. 63) 95 a. 10-13 137 b. 14 C ardens 95 (94). Scales a. absent, incomplete, or uncountable (Fig. 105 (32). Number of principal dorsal fin rays 63) C. latipinnis a. 10 C commersoni

88 b. 11 149 a. 11 C. latipinnis c. 12-13 142 b. 12-14 176 d. 14 176 c. 15-16 X. texanus e. 15-16 X. texanus 116 (75,96). Number of lateral rows of scales 106 (83A,83B,84). Number of lateral rows of beginning with first lateral line scale scales beginning with first lateral (equals lateral line scale count if line scale (equals lateral line scale lateral line is complete and observ- count if lateral line is complete and able to base of caudal fin) observable to base of caudal fin) a. 60-77 C platyrhynchus a. 53-67 C commersoni b. 78-108 117 b. 68-85 107 c. 109-122 C. discobolus c. 86-95 X. texanus 117 (57,75,96,116). Pigment outlining scales 107 (32,36,55,66,69,98,106). Pigment outlining a. absent or light (Figs. 49, 77) 182 scales b. bold (Fig. 21) C platyrhynchus a. absent or light (Fig. 91) 108 b. bold (Fig. 35) C commersoni 118 (97). Mid-lateral surface of body with a. no large, distinct spots (Figs. 21, 63, 108 (20,36,107). Number of principal dorsal fin 91) 119 rays b. 2 large, distinct spots, one between head a. 10-11 C commersoni and dorsal fin and the other over the b. 12-13 153 pelvic fin ...... C. ardens c. 14-16 X. texanus c. 3 large, distinct spots, one between head and dorsal fin, the second over the 109 (95). Number of lateral rows of scales pelvic fin, and the last on the caudal beginning with first lateral line scale peduncle near the base of the tail (Fig. (equals lateral line scale count if 35) C. commersoni lateral line is complete and observable to base of caudal fin) 119 (118). Ventral midline from shortly behind a. 54-79 C ardens heart region to near vent with b. 89-120 C. latipinnis a. L-21 melanophores in a continuous or discontinuous line or narrow band (Fig. 110 (45). Pigment outlining scales 34) C commersoni a. absent or light (Figs. 20, 91) 111 b. 7-20 melanophores 127 b. bold (Fig. 21) C ardens C. melanophores (Figs. 20, 62, 90) . . 120

111 (12,110). Number of principal dorsal fin rays 120 (119). Pigment over ventral to ventro-lateral a. 10-11 C. ardens surfaces of gill covers (opercula) b. 12-14 170 a. absent (Figs. 62, 90) ...... 121 c. L5-16 X. texanus b. present in a distinct oblique row of 3 or more melanophores near or along ven- 112 (90). Number of lateral rows of scales tral margin of one or both preopercles beginning with first lateral line scale (Fig. 31) C. commersoni (equals lateral line scale count if C. present but not in distinct oblique rows lateral line is complete and observ- (Figs. 21, 34) 133 able to base of caudal fin) a. 53-85 C commersoni 121 (120). Pigmentation on lateral surfaces of b. 89-120 C. latipinnis body above bottom-of-eye level and anterior to vent, exclusive of melan- 113 (33). Number of principal dorsal fin rays ophores associated with horizontal a. 10 C commersoni myosepta, air bladder, visceral cavity b. 11-13 149 (peritoneum), or gut, c. 14 C. latipinnis a. scattered only partially down to the horizontal myoseptum (lateral midline) 114 (92). Number of lateral rows of scales (Fig. 90) X. texanus beginning with first lateral line scale b. scattered fully and evenly down to the (equals lateral line scale count if horizontal myoseptum with few if any lateral line is complete and observ- melanophores below the myoseptum able to base of caudal fin) (Fig. 62) ...... 146 a. 68-88 X. texanus C. scattered evenly or in blotchy pattern b. 89-95 115 (continuous with dorsal and c. 96-120 C. latipinnis dorso-lateral surface pattern) down to horizontal myoseptum and at least 115 (25,45,48,81B,83B,114). Number of principal partially to bottom- of-eye level below dorsal fin rays (Figs. 20, 35, 63, 91) 122

89 122 (121). Pigmentation on lateral to b. scattered evenly or in blotchy pattern ventro-lateral surfaces of body below (continuous with dorsal and dorso- bottom-of-eye level, exclusive of lateral surface pattern) down to hori- melanophores associated with horizontal myoseptum and at least partially zontal myosepta, air bladder, vis- to bottom- of-eye level below (Figs. 20, ceral cavity (peritoneum), or gut, 63) 129 a. absent including caudal peduncle (Figs 62, 91) 147 129 (128). Pigmentation on lateral to ventro- b. absent except on caudal peduncle (Figs lateral surfaces of body below 20, 21) 123 bottom-of-eye level, exclusive of c. present anterior to caudal peduncle (Fig melanophores associated with hori- 35) 135 zontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 123 (122). Pigment in caudal fm a. absent including caudal peduncle (Fig a. along fin rays with very few, if any, 62) 238 melanophores on membrane between b. absent except on caudal peduncle (Figs rays (Fig. 35) 208 20, 21) 208 b. abundant both along and between rays c. present anterior to caudal peduncle (Fig (Figs. 63, 91) 124 35) 247

124 (123). Pigment in dorsal fin 130 (100). Mid-lateral surface of body with a. along fin rays with very few, if any, a. no large, distinct spots (Figs. 21, 34, melanophores on membrane between 90) 131 rays (Fig. 62) 208 b. 2 large, distinct spots, one between head b. abundant both along and between rays and dorsal fin and the other over the (Figs. 63, 91) 187 pelvic fin ...... C. ardens c. 3 large, distinct spots, one between head 125 (97,102). Mid-lateral surface of body with and dorsal fin, the second over the a. no large, distinct spots (Figs. 21, 62) . . 126 pelvic fin, and the last on the caudal b. 2 large, distinct spots, one between head peduncle near the base of the tail (Fig. and dorsal fin and the other over the 35) C commersoni pelvic fin ...... C. ardens c. 3 large, distinct spots, one between head 131 (130). Ventral midline from shortly behind and dorsal fin, the second over the pelvic heart region to near vent with fin, and the last on the caudal peduncle a. -21_ melanophores in a continuous or near the base of the tail (Fig. 35) discontinuous line or narrow band (Fig. C commersoni 34) C commersoni b. 7-20 melanophores 139 126 (125). Ventral midline from shortly behind c. 6 melanophores (Figs. 20, 90) 132 heart region to near vent with a. ?-_21 melanophores in a continuous or 132 (131). Pigment over ventral to ventro-lateral discontinuous line or narrow band (Fig. surfaces of gill covers (opercula) 34) C cornmersoni a. absent or present but not in distinct b. -5720 melanophores (Figs. 20, 62) 127 oblique rows (Figs. 20, 91) 133 b. present in a distinct oblique row of 3 or 127 (119,126). Pigment over ventral to more melanophores near or along ven- ventro-lateral surfaces of gill covers tral margin of one or both preopercles (opercula) (Fig. 31) C commersoni a. absent (Figs. 20, 62) 128 b. present in a distinct oblique row of 3 or 133 (120,132). Pigmentation on lateral surfaces more melanophores near or along of body above bottom-of-eye level ventral margin of one or both and anterior to vent, exclusive of preopercles (Fig. 31) C commersoni melanophores associated with hori- c. present but not in distinct oblique rows zontal myosepta, air bladder, vis- (Figs. 21, 34) 140 ceral cavity (peritoneum), or gut, a. scattered only partially down to the 128 (127). Pigmentation on lateral surfaces of horizontal myoseptum (lateral midline) body above bottom-of-eye level and (Fig. 90) X. te:canus anterior to vent, exclusive of melan- b. scattered fully and evenly down to the ophores associated with horizontal horizontal myoseptum with few if any myosepta, air bladder, visceral cavity melanophores below the myoseptum (peritoneum), or gut, (Fig. 62) 157 a. scattered fully and evenly down to the c. scattered evenly or in blotchy pattern horizontal myoseptum with few if any (continuous with dorsal and dorso- melanophores below the myoseptum lateral surface pattern) down to (Fig. 62) 152 horizontal myoseptum and at least

90 partially to bottom-of-eye level below melanophores below the myoseptum (Figs. 20, 91) 134 C commersoni b. scattered evenly or in blotchy pattern 134 (133). Pigmentation on lateral to ventro- (continuous with dorsal and dorso- lateral surfaces of body below lateral surface pattern) down to hori- bottom-of-eye level, exclusive of zontal myoseptum and at least partially melanophores associated with hori- to bottom-of-eye level below (Figs. 20, zontal myosepta, air bladder, vis- 21, 35) 141 ceral cavity (peritoneum), or gut, a. absent including caudal peduncle (Fig 141 (140). Pigmentation on lateral to ventro- 91) 157 lateral surfaces of body below b. present at least on caudal peduncle bottom-of-eye level, exclusive of (Figs. 20, 21, 35) 135 melanophores associated with horizontal myosepta, air bladder, vis- 135 (122,134). Pigment in caudal fin ceral cavity (peritoneum), or gut, a. along fm rays with very few, if any, a. absent including caudal peduncle melanophores on membrane between ...... C. commersoni rays (Fig. 35) 247 b. present at least on caudal peduncle b. abundant both along and between rays (Figs. 20, 21, 35) 247 (Fig. 91) 136 142 (105). Mid-lateral surface of body with 136 (135). Pigment in dorsal fin a. no large, distinct spots (Figs. 63, 91) . . 143 a. along fin rays with very few, if any, b. 3 large, distinct spots, one between head melanophores on membrane between and dorsal fin, the second over the rays (Fig. 21) 247 pelvic fm, and the last on the caudal b. abundant both along and between rays peduncle near the base of the tail (Fig. (Fig. 91) 198 35) C. commersoni

137 (97,100,102,104). Mid-lateral surface of body 143 (142). Ventral midline from shortly behind with heart region to near vent with a. no large, distinct spots (Figs. 21, 34) . . 138 a. .?:21 melanophores in a continuous or b. 2 large, distinct spots, one between head discontinuous line or narrow band (Fig. and dorsal fm and the other over the 34) C commersoni pelvic fin C. ardens b. 7-20 melanophores 151 c. 3 large, distinct spots, one between head c. melanophores (Figs. 35, 63, 91) . . 144 and dorsal fin, the second over the pelvic fm, and the last on the caudal peduncle 144 (143). Pigment over ventral to ventro-lateral near the base of the tail (Fig. 35) surfaces of gill covers (opercula) C commersoni a. absent (Figs. 35, 63, 91) 145 b. present in a distinct oblique row of 3 or 138 (137). Ventral midline from shortly behind more melanophores near or along ven- heart region to near vent with tral margin of one or both preoperdes a. melanophores in a continuous or (Fig. 31) C commersoni discontinuous line or narrow band (Fig. c. present but not in distinct oblique 34) C commersoni rows ...... 156 b. melanophores (Figs. 20, 21, 35) . . 139 145 (144). Pigmentation on lateral surfaces of 139 (131,138). Pigment over ventral to ventro- body above bottom-of-eye level and lateral surfaces of gill covers anterior to vent, exclusive of melan- (opercula) ophores associated with horizontal a. absent or present but not in distinct myosepta, air bladder, visceral cavity oblique rows (Figs. 20, 34) 140 (peritoneum), or gut, b. present in a distinct oblique row of 3 or a. scattered only partially down to the more melanophores near or along ven- horizontal myoseptum (lateral midline) tral margin of one or both preopercles (Fig. 90) X. texanus (Fig. 31) C commersoni b. scattered evenly or in blotchy pattern (continuous with dorsal and dorso- 140 (127,139). Pigmentation on lateral surfaces lateral surface pattern) down to hori- of body above bottom-of-eye level zontal myoseptum and sometimes at and anterior to vent, exclusive of least partially to bottom-of-eye level melanophores associated with hori- below (Figs. 35, 62, 91) 146 zontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 146 (121,145). Pigmentation on lateral to a. scattered fully and evenly down to the ventro-lateral surfaces of body horizontal myoseptum with few if any below bottom-of-eye level, exclusive

91 of melanophores associated with 154 (153). Ventral midline from shortly behind horizontal myosepta, air bladder, heart region to near vent with visceral cavity (peritoneum), or gut, a. ?_.7 melanophores in a continuous or a. absent anterior to caudal peduncle (Figs discontinuous line or narrow band (Fig. 62, 91) 147 34) C commersoni b. present anterior to caudal peduncle (Fig b. melanophores (Figs. 35, 91) 155 35) 157 155 (154). Pigment over ventral to ventro-lateral 147 (122,146). Pigment in caudal fin surfaces of gill covers (opercula) a. along fin rays with very few, if any, a. absent or present but not in distinct melanophores on membrane between oblique rows (Figs. 35, 91) 156 rays (Figs. 35, 62) 238 b. present in a distinct oblique row of 3 or b. abundant both along and between rays more melanophores near or along ven- (Figs. 63, 91) 148 tral margin of one or both preopercles (Fig. 31) C commersoni 148 (147). Pigment in dorsal fin a. along fin rays with very few, if any, 156 (144,155). Pigmentation on lateral surfaces melanophores on membrane between of body above bottom-of-eye level rays (Fig. 62) 238 and anterior to vent, exclusive of b. abundant both along and between rays melanophores associated with hori- (Figs. 63, 91) 188 zontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 149 (105,113). Mid-lateral surface of body with a. scattered only partially down to the a. no large, distinct spots (Figs. 34, 63) . . 150 horizontal myoseptum (lateral midline) b. 3 large, distinct spots, one between head (Fig. 90) X. texanus and dorsal fin, the second over the pelvic b. scattered evenly or in blotchy pattern fin, and the last on the caudal peduncle (continuous with dorsal and dorso- near the base of the tail (Fig. 35) lateral surface pattern) down to hori- C commersoni zontal myoseptum and sometimes at least partially to bottom-of-eye level 150 (149). Ventral midline from shortly behind below (Figs. 35, 91) 157 heart region to near vent with a. -_21 melanophores in a continuous or 157 (133,134,146,156). Pigment in caudal fin discontinuous line or narrow band (Fig. a. along fm rays with very few, if any, 34) C commersoni melanophores on membrane between b. 213 melanophores (Figs. 35, 63) 151 rays (Fig. 35) C commersoni b. abundant both along and between rays 151 (143,150). Pigment over ventral to ventro- (Fig. 91) 158 lateral surfaces of gill covers (opercula) 158 (157). Pigment in dorsal fin a. absent (Figs. 35, 63) 152 a. along fm rays with very few, if any, b. present, sometimes in a distinct oblique melanophores on membrane between row of 3 or more melanophores near or rays (Fig. 35) C commersoni along ventral margin of one or both b. abundant both along and between rays preopercles (Fig. 31) C commersoni (Fig. 91) 229

152 (128,151). Pigmentation on lateral to ventro- 159 (97). Mid-lateral surface of body with lateral surfaces of body below a. no large, distinct spots (Figs. 21, 63, bottom-of-eye level, exclusive of 91) 160 melanophores associated with hori- b. 2 large, distinct spots, one between head zontal myosepta, air bladder, vis- and dorsal fin and the other over the ceral cavity (peritoneum), or gut, pelvic fin ...... C. ardens a. absent anterior to caudal peduncle (Fig 63) 238 160 (159). Ventral midline from shortly behind b. present anterior to caudal peduncle (Fig heart region to near vent with 35) C. commersoni a. 7-20 melanophores 167 b. melanophores (Figs. 21, 63, 91) . . 161 153 (108). Mid-lateral surface of body with a. no large, distinct spots (Fig. 91) 161 (160). Pigment over ventral to ventro-lateral 154 surfaces of gill covers (opercula) b. 3 large, distinct spots, one between head a. absent (Figs. 63, 91) 162 and dorsal fin, the second over the pelvic b. present but not in distinct oblique rows fin, and the last on the caudal peduncle (Figs. 21) 172 near the base of the tail (Fig. 35) C commersoni 162 (161). Pigmentation on lateral surfaces of

92 body above bottom-of-eye level and a. scattered fully and evenly down to the level and anterior to vent, exclusive horizontal myoseptum with few if any of melanophores associated with melanophores below the myoseptum horizontal myosepta, air bladder, (Fig. 62) C. laupinnis visceral cavity (peritoneum), or gut, b. scattered evenly or in blotchy pattern a. scattered only partially down to the (continuous with dorsal and dorso- horizontal myoseptum (lateral midline; lateral surface pattern) down to Fig. 90) X. texanus horizontal myoseptum and at least b. scattered fully and evenly down to the partially to bottom-of-eye level below horizontal myoseptum with few if any (Figs. 20, 21, 63) 169 melanophores below the myoseptum (Fig. 62) 179 169 (168). Pigmentation on lateral to ventro- c. scattered evenly or in blotchy pattern lateral surfaces of body below (continuous with dorsal and dorso-lateral bottom-of-eye level, exclusive of surface pattern) down to horizontal melanophores associated with hori- myoseptum and at least partially to zontal myosepta, air bladder, vis- bottom-of-eye level below (Figs. 63, ceral cavity (peritoneum), or gut, 91) 163 a. absent including caudal peduncle (Fig. 62) C. latipinnis 163 (162). Pigmentation on lateral to ventro- b. absent except on caudal peduncle (Figs. lateral surfaces of body below 21, 63) 255 bottom-of-eye level, exclusive of c. present anterior to caudal peduncle (Fig melanophores associated with hori- 35) C. ardens zontal myosepta, air bladder, visceral cavity (peritoneum), or gut, 170 (100,111). Mid-lateral surface of body with a. absent including caudal peduncle (Figs a. no large, distinct spots (Figs. 21, 91) . . 171 62, 91) 180 b. 2 large, distinct spots, one between head b. absent except on caudal peduncle (Figs and dorsal fin and the other over the 21, 63) 164 pelvic fin ...... C. ardens c. present anterior to caudal peduncle (Fig 35) 174 171 (170). Ventral midline from shortly behind heart region to near vent with 164 (163). Pigment in caudal fin a. 7-20 melanophores C. ardens a. along fin rays with very few, if any, b. melanophores (Figs. 20, 21, 90, 91) 172 melanophores on membrane between rays (Fig. 20) 2.55 172 (161,171). Pigmentation on lateral surfaces b. abundant both along and between rays of body above bottom-of-eye level (Figs. 21, 63, 91) 165 and anterior to vent, exclusive of melanophores associated with hori- 165 (164). Pigment in dorsal fm zontal myosepta, air bladder, vis- a. along fin rays with very few, if any, ceral cavity (peritoneum), or gut, melanophores on membrane between a. scattered partially or fully and evenly rays (Figs. 20, 62) 255 down to the horizontal myoseptum with b. abundant both along and between rays few if any melanophores below the myo- (Figs. 21, 63, 91) 209 septum (Fig. 62) X. texanus b. scattered evenly or in blotchy pattern 166 (102). Mid-lateral surface of body with (continuous with dorsal and dorso- a. no large, distinct spots (Figs. 21, 63) . . 167 lateral surface pattern) down to b. 2 large, distinct spots, one between head horizontal myoseptum and at least and dorsal fm and the other over the partially to bottom-of-eye level below pelvic fm C ardens (Figs. 20, 21, 91) 173

167 (160,166). Pigment over ventral to ventro- 173 (172). Pigmentation on lateral to ventro- lateral surfaces of gill covers lateral surfaces of body below (opercula) bottom-of-eye level, exclusive of a. absent (Fig. 63) 168 melanophores associated with hori- b. present but not in distinct oblique rows zontal myosepta, air bladder, vis- (Fig. 21) C ardens ceral cavity (peritoneum), or gut, a. absent including caudal peduncle (Fig. 168 (167). Pigmentation on lateral surfaces of 91) X. texanus body above bottom-of-eye level and b. present, at least on caudal peduncle anterior to vent, exclusive of melan- (Figs. 20, 21) 174 ophores associated with horizontal myosepta, air bladder, visceral cavity 174 (163,173). Pigment in caudal fin (peritoneum), or gut, a. along fin rays with very few, if any,

93 melanophores on membrane between 182 (39,117). Ventral midline from shortly be- rays (Fig. 20) C. ardens hind heart region to near vent with b. abundant both along and between rays a. L-21 melanophores in a continuous or (Figs. 21, 91) 175 discontinuous line or narrow band (Fig. 75) C. platyrhynchus 175 (174). Pigment in dorsal fin b. -s.20 melanophores (Figs. 48, 49, 76, a. along fin rays with very few, if any, 77) 183 melanophores on membrane between rays (Fig. 20) C. ardens 183 (182). Pigment over ventral to ventro-lateral b. abundant both along and between rays surfaces of gill covers (opercula) (Figs. 21, 91) 220 a. absent (Figs. 48, 49, 76) 184 b. present but not in distinct oblique rows 176 (105,115). Ventral midline from shortly (Fig. 77) C. platyrhynchus behind heart region to near vent with 184 (183). Pigmentation on lateral surfaces of a. 7-20 melanophores C. latipinnis body above bottom-of-eye level and b. melanophores (Figs. 63, 91) 177 anterior to vent, exclusive of melanophores associated with hori- 177 (176). Pigment over ventral to ventro-lateral zontal myosepta, air bladder, vis- surfaces of gill covers (opercula) ceral cavity (peritoneum), or gut, a. absent (Figs. 63, 91) 178 a. scattered fully and evenly down to the b. present but not in distinct oblique rows horizontal myoseptum with few if any ...... X. teranus melanophores below the myoseptum C platyrhynchus 178 (177). Pigmentation on lateral surfaces of b. scattered evenly or in blotchy pattern body above bottom-of-eye level and (continuous with dorsal and dorso- anterior to vent, exclusive of melan- lateral surface pattern) down to ophores associated with horizontal horizontal myoseptum and at least myosepta, air bladder, visceral cavity partially to bottom-of-eye level below (peritoneum), or gut, (Figs. 48, 49, 76, 77) 185 a. scattered only partially down to the horizontal myoseptum (lateral midline) 185 (184). Pigmentation on lateral to ventro- (Fig. 90) X. texanus lateral surfaces of body below b. scattered evenly or in blotchy pattern bottom-of-eye level, exclusive of (continuous with dorsal and dorso-lateral melanophores associated with hori- surface pattern) down to horizontal zontal myosepta, air bladder, vis- myoseptum and sometimes at least ceral cavity (peritoneum), or gut, partially to bottom- of-eye level below a. absent anterior to caudal peduncle (Figs (Figs. 63, 91) 179 48, 49, 76) 186 b. present anterior to caudal peduncle (Fig 179 (162,178). Pigmentation on lateral to ventro- 77) C. platyrhynchus lateral surfaces of body below bottom-of-eye level, exclusive of 186 (185). Pigment in dorsal fm melanophores associated with hori- a. along fin rays with very few, if any, zontal myosepta, air bladder, vis- melanophores on membrane between ceral cavity (peritoneum), or gut, rays (Figs. 48, 77) 256 a. absent anterior to caudal peduncle (Figs b. abundant both along and between rays 62, 62, 91) 180 ...... C. platyrhynchus b. present anterior to caudal peduncle ...... X. texanus 187 (124). Longitudinal eye diameter 180 (163,179). Pigment in caudal fin a. 19-20% of head length ...... C. latipinnis a. along fm rays with very few, if any, b. 21% of head length ...... 211 melanophores on membrane between c. 22-26% of head length ...... 189 rays ...... C. latipinnis d. 27-28% of head length ...... 199 b. abundant both along and between rays e. 29-30% of head length ...... 221 (Figs. 63, 90, 91) 181 f. 31-32% of head length ...... C. ardens

181 (180). Pigment in dorsal fm 188 (148). Longitudinal eye diameter a. along fin rays with very few, if any, a. 19-20% of head length ...... C. latipinnis melanophores on membrane between b. 21% of head length ...... 211 rays (Fig. 62) C. latipinnis c. 22-26% of head length ...... 189 b. abundant both along and between rays d. 27-28% of head length ...... 230 (Figs. 63, 90, 91) 210 e. 29-30% of head length ...... X. texanus

94 189 (187,188). Length of base of dorsal fm 198 (136). Longitudinal eye diameter (origin to insertion of dorsal fin) a. 21% of head length X. texanus a. 13% SL commersoni b. 22-26% of head length ...... 230 b. 14-15% SL ...... 240 c. 27-28% of head length ...... 199 c. 16% SL 190 d. 29-30% of head length ...... 221 d. 17-18% SL 212 e. 31-32% of head length ...... C. ardens e. 19-20% SL X. teranus 199 (187,198). Length of base of dorsal fin 190 (189). Dorsal fm length (origin to insertion of dorsal fm) a. 18-22% SL C commersoni a. 13% SL C commersoni b. 23-24% SL 191 b. 14-15% SL 249 c. 25-26% SL 213 c. 16% SL 200 d. 27-29% SL X. te:canus d. 17% SL 222 e. 18-20% SL X. texanus 191 (190). Caudal fin length (total length minus standard length) 200 (199). Dorsal fin length a. 19-20% SL commersoni a. 18-20% SL C commersoni b. 21-22% SL 242 b. 21-22% SL 250 c. 23-24% SL 192 c. 23-24% SL 201 d. 25% SL 214 d. 25-26% SL 223 e. 26-28% SL X. texanus e. 27-29% SL X. texanus

192 (191). Depth at origin of dorsal fin 201 (200). Caudal fin length (total length minus a. 17% SL 242 standard length) b. 18-22% SL 193 a. 19-22% SL C commersoni c. 23-27% SL X. tetanus b. 23-24% SL ...... 202 c. 25-28% SL 224 193 (192). Length from anterior margin of snout to insertion of dorsal fm 202 (201). Depth at origin of dorsal fin a. 61-64% SL 243 a. 16% SL C. ardens b. 65-66% SL 194 b. 17% SL 252 c. 67-68% SL 235 c. 18-22% SL 203 d. 69-70% SL X. texanus d. 23-27% SL X. texanus

194 (193). Length from anterior margin of snout 203 (202). Length from anterior margin of snout to origin of dorsal fin to insertion of dorsal fin a. 46-47% SL 217 a. 61-63% SL C commersoni b. 48-49% SL 195 b. 64% SL 253 c. 51-52% SL 236 c. 65-66% SL 204 d. 53% SL C commersoni d. 67-68% SL 235 e. 69-70% SL X. texanus 195 (194). Length from anterior margin of snout to origin of pelvic fin 204 (203). Length from anterior margin of snout a. 52-53% SL 245 to origin of dorsal fin b. 54-57% SL 196 a. 46-47% SL X. texanus c. 58-60% SL 236 b. 48-51% SL 205 c. 52% SL 236 196 (195). Length from anterior margin of snout d. 53% SL C. commersoni to posterior margin of the vent a. 72-74% SL 246 205 (204). Length from anterior margin of snout b. 75-76% SL 197 to origin of pelvic fin c. 77-78% SL 237 a. 52-53% SL C. commersoni d. 79-80% SL X. texanus b. 54-58% SL 206 c. 59-60% SL. 236 197(1%). Length from anterior margin of snout to origin of pectoral fin 206 (205). Length from anterior margin of snout a. 24% SL C commersoni to posterior margin of vent C. latipinnis a. 72-74% SL 254 b. 25-28% SL C commersoni b. 75-76% SL 207 C. latipinnis c. 77-78% SL 237 X. texanus d. 79-80% SL X. texanus c. 29% SL C commersoni X. texanus 207 (206). Length from anterior margin of snout d. 30-31% SL X. texanus to origin of pectoral fin

95 a. 24% SL C commersoni a. 24% SL C. latipinnis b. 25-28% SL C ardens b. 25-28% SL 219 C. commersoni c. 29-31% SL X. texanus X. texanus c. 29% SL C commersoni 219 (218). Length from anterior margin of snout X. texanus to posterior margin of vent d. 30-31% SL X. tetanus a. 72-74% SL C. latipinnis b. 75-76% SL C. latipinnis 208 (123,124,129). Longitudinal eye diameter X. texanus a. 19-21% of head length ...... C. latipinnis c. 77-80% SL X. texanus b. 22-26% of head length ...... 239 c. 27-28% of head length ...... 248 220 (175). Longitudinal eye diameter d. 29-32% of head length ...... C. ardens a. 21-26% of head length ...... X. texanus b. 27-30% of head length ...... 221 209 (165). Longitudinal eye diameter c. 31-32% of head length ...... C. ardens a. 19-20% of head length ...... C. latipinnis b. 21-26% of head length ...... 211 221 (187,198,209,220). Length of base of dorsal c. 27-30% of head length ...... 221 fin (origin to insertion of dorsal fin) d. 31-32% of head length ...... C. ardens a. 14-15% SL C. ardens b. 16-17% SL 222 210 (181). Longitudinal eye diameter c. 18-20% SL X. texanus a. 19-20% of head length ...... C. latipinnis b. 21-26% of head length ...... 211 c. 27-30% of head length ...... X. texanus 222 (199,221). Dorsal fin length 211 (187,188,209,210). Length of base of dorsal a. 19-22% SL C. ardens fin (origin to insertion of dorsal fin) b. 23-26% SL 223 a. 14-15% SL C. latipinnis c. 27-29% SL X. texanus b. 16-18% SL 212 c. 19-20% SL X. texanus 223 (200,222). Depth at origin of dorsal fin a. 16-17% SL C. ardens 212 (189,211). Dorsal fm length b. 18-22% SL 224 a. 23-26% SL 213 c. 23-27% SL X. texanus b. 27-29% SL X. teranus 224 (201,223). Length from anterior margin of 213 (190,212). Caudal fin length (total length snout to insertion of dorsal fin minus standard length) a. 64% SL C. ardens a. 21-22% SL C. latipinnis b. 65-66% SL 225 b. 23-25% SL 214 c. 67-70% SL X. texanus c. 26-28% SL X. texanus 225 (224). Length from anterior margin of snout 214 (191,213). Depth at origin of dorsal fin to origin of dorsal fin a. 17% SL C. latipinnis a. 46-47% SL X. texanus b. 18-22% SL 215 b. 48-52% SL 226 c. 23-27% SL X. texanus 226 (225). Length from anterior margin of snout 215 (214). Length from anterior margin of snout to posterior margin of vent to insertion of dorsal fin a. 73-74% SL C. ardens a. 61-64% SL C. latipinnis b. 75-76% SL 227 b. 65-66% SL 216 c. 77-80% SL X. texanus c. 67-70% SL X. texanus 227 (226). Length from anterior margin of snout 216 (215). Length from anterior margin of snout to origin of pelvic fin to origin of dorsal fm a. 54-58% SL 228 a. 46-49% SL 217 b. 59-60% SL X. texanus b. 50-52% SL X. texanus 228 (227). Length from anterior margin of snout 217 (194,216). Length from anterior margin of to origin of pectoral fin snout to origin of pelvic fin a. 25-28% SL C. ardens a. 52-53% SL C. latipinnis X. texanus b. 54-57% SL 218 b. 29-31% SL X. texanus c. 58-60% SL X. texanus

218 (217). Length from anterior margin of snout 229 (158). Longitudinal eye diameter to origin of pectoral fin a. 21% of head length ...... X. texanus

96 b. 22-28% of head length ...... 230 b. 23-24% SL 241 c. 29-30% of head length ...... X. texanus c. 25-26% SL C. latipinnis

230 (188,198,229). Length of base of dorsal fin 241 (240). Caudal fin length (total length minus (origin to insertion of dorsal fin) standard length) a. 13-15% SL C commersoni a. 19-20% SL C. commersoni b. 16% SL 231 b. 21-24% SL 242 c. 17-20% SL X. texanus c. 25% SL C. latipinnis

231 (230). Dorsal fin length 242 (191,192,241). Length from anterior margin a. 18-22% SL C commersoni of snout to insertion of dorsal fin b. 23-24% SL 232 a. 61-66% SL 243 c. 25-29% SL X. texanus b. 67-68% SL C commersoni

232 (231). Caudal fm length (total length minus 243 (193,242). Length from anterior margin of standard length) snout to origin of dorsal fin a. 19-22% SL C commersoni a. 46-47% SL C. latipinnis b. 23-24% SL 233 b. 48-49% SL 244 c. 25-28% SL X. tetanus c. 50-53% SL C commersoni

233 (232). Depth at origin of dorsal fin 244 (243). Length from anterior margin of snout a. 17% SL C. commersoni to origin of pelvic fin b. 18-22% SL 234 a. 52-57% SL 245 c. 23-27% SL X. texanus b. 58-59% SL C commersoni

234 (233). Length from anterior margin of snout 245 (195,244). Length from anterior margin of to insertion of dorsal fin snout to posterior margin of vent a. 61-64% SL C commersoni a. 72-76% SL 246 b. 65-68% SL 235 b. 77-78% SL C. commersoni c. 69-70% SL X. texanus 246 (196,245). Length from anterior margin of 235 (193,203,234). Length from anterior margin snout to origin of pectoral fin of snout to origin of dorsal fin a. 24-28% SL C. commersoni a. 46-47% SL X. texanus C. latipinnis b. 48-52% SL 236 b. 29% SL C. commersoni c. 53% SL C commersoni 247(129,135,136,141). Longitudinal eye diameter 236 (194,195,204,205,235). Length from anterior a. 22-26% of head length . . C. commersoni margin of snout to posterior margin b. 27-28% of head length ...... 248 of vent c. 29-32% of head length ...... C. ardens a. 72-74% SL C commersoni b. 75-78% SL 237 248 (208,247). Length of base of dorsal fin c. 79-80% SL X. texanus (origin to insertion of dorsal fm) a. 13% SL C commersoni 237 (196,206,236). Length from anterior margin of b. 14-16% SL 249 snout to origin of pectoral fin c. 17% SL C. ardens a. 24% SL C commersoni b. 25-29% SL C commersoni 249 (199,248). Dorsal fin length X. texanus a. 18% SL C. commersoni c. 30-31% SL X. texanus b. 19-24% SL 250 c. 25-26% SL C. ardens 238(129,147,148,152). Longitudinal eye diameter a. 19-21% of head length ...... C. latipinnis 250 (200,249). Caudal fin length (total length b. 22-26% of head length ...... 239 minus standard length) c. 27-28% of head length . . . . C. commersoni a. 19-22% SL C. commersoni b. 23-24% SL 251 239 (208,238). Length of base of dorsal fin c. 25-28% SL C. ardens (origin to insertion of dorsal fin) a. 13% SL C commersoni 251 (250). Depth at origin of dorsal fm b. 1446% SL 240 a. 16% SL C. ardens c. 17-18% SL C. latipinnis b. 17-22% SL 252

240 (189,239). Dorsal fin length 252 (202,251). Length from anterior margin of a. 18-22% SL C commersoni snout to insertion of dorsal fin

97 a. 61-63% SL C commersoni Skeletal Character Key for Juveniles :540 mm b. 64-66% SL 253 SL that have been cleared and preferably c. 67-68% SL C commersoni stained for bone (Fig. 6). 253 (203,252). Length from anterior margin of snout to origin of dorsal fin 1. Standard length group (Fig. 4) a. 48-51% SL 254 a. mm 2 b. 52-53% SL b. 22-25 mm 4 C commersoni c. 26-34 mm 5 254 (206,253). Length from anterior margin of d. mm 9 snout to origin of pectoral fin a. 24-28% SL C. ardens 2 (1). First (most anterior) interneural bone C. commersoni (Fig. 8) b. 29% SL C commersoni a. large and angular or anvil-shaped with a prominent posterior-directed 255 (164,165,169). Longitudinal eye diameter projection or beak; anterior ends of a. 19-26% of head length ...... C. latipinnis mandibles (from ventral view of head) b. 27-32% of head length ...... ardens well anterior, at least mid-distance C. between posterior and anterior ends of 256 (186). Longitudinal eye diameter maxillae; anterior-dorsal maxillary a. 21-25% of head length ...... 257 projections small and rounded to b. 26-28% of head length ...... C. discobolus reduced and almost absent ...... 3 b. small and blocky, sometimes with a 257 (256). Length of base of dorsal fin (origin to small posterior- directed projection or insertion of dorsal fin) beak; anterior ends of mandibles (from a. 11-14% SL 258 ventral view of head) well posterior, b. 15-16% SL C. discobolus much closer to posterior than anterior ends of maxillae; anterior-dorsal 258 (257). Dorsal fin length maxillary projections prominent and a. 18% SL C. platyrhynchus pointed ...... 11 b. 19-21% SL 259 c. 22-23% SL C. discobolus 3 (2). Number of vertebrae (including 4 for Weberian complex) 259 (258). Caudal fm length (total length minus a. 44-46 C commersoni standard length) b. 47-48 C. ardens a. 19% SL C. platyrhynchus C. commersoni b. 20-23% SL 260 c. 24% SL C. discobolus 4 (1). Frontoparietal fontanelle (Fig. 7) a. narrow, 0(70 of fontanelle length . 11 260 (259). Depth at origin of dorsal fin b. moderately wide, 31-40% of fontanelle a. 16-17% SL C. discobolus length ...... 6 b. 18-21% SL 261 c. wide, 41-47% of fontanelle length ...... 8 d. very wide, .48%. of fontanelle length 261 (260). Length from anterior margin of snout (often over 60% and somewhat oval in to insertion of dorsal fin shape) ...... a. 60-61% SL C. platyrhynchus ...... X. texanus b. 62-64% SL 262 c. 65-66% SL C. discobolus 5 (1). Frontoparietal fontanelle (Fig. 7) a. very narrow, 4% of fontanelle 262 (261). Length from anterior margin of snout length ...... to origin of dorsal fm ...... C. platyrhynchus a. 47-52% SL 263 b. narrow, 24-28% of fontanelle length ... 11 b. 53-54% SL C. discobolus c. moderately wide, 29-40% of fontanelle length ...... 6 263 (262). Length from anterior margin of snout d. wide, 41-47% of fontanelle length ...... 7 to posterior margin of vent e. very wide, ?s48% of fontanelle length a. 72-73% SL C. discobolus (usually somewhat oval in shape) X. texanus b. 74-76% SL C. discobolus C. platyrhynchus 6 (4,5). First (most anterior) interneural bone c. 77-78% SL C. platyrhynchus (Fig. 8)

98 a. large and angular or anvil-shaped with a posterior and anterior ends of maxillae; prominent posterior-directed projection anterior-dorsal maxillary projections or beak; anterior ends of mandibles small and rounded to reduced and (from ventral view of head) well anter- almost absent C commersoni ior, at least mid-distance between b. small and blocky, sometimes with a posterior and anterior ends of maxillae; small posterior-directed projection or anterior-dorsal maxillary projections beak; anterior ends of mandibles (from small and rounded to reduced and ventral view of head) well posterior, almost absent ...... 8 much closer to posterior than anterior b. small and blocky, sometimes with a ends of maxillae; anterior-dorsal small posterior-directed projection or maxillary projections prominent and beak; anterior ends of mandibles (from pointed ...... 11 ventral view of head) well posterior, much closer to posterior than anterior 11(2,4,5,6,10). Number of vertebrae (including ends of maxillae; anterior-dorsal 4 for Weberian complex) maxillary projections prominent and a. 42-44 C. platyrhynchus pointed ...... 11 b. 45-50 C. discobolus C. platyrhynchus 7 (5). First (most anterior) interneural bone (Fig. 8) 12 (9). First (most anterior) interneural bone a. large and fan-shaped across top X. texanus (Fig. 8) b. large and angular or anvil-shaped with a a. large and angular or anvil-shaped with prominent posterior-directed projection a prominent posterior-directed projec- or beak 8 tion or beak; anterior ends of mandibles (from ventral view of head) well anterior, at least mid-distance between 8 (4,6,7). Number of vertebrae (including 4 for posterior and anterior ends of maxillae; Weberian complex) anterior-dorsal maxillary projections a. 44-46 C. commersoni small and rounded to reduced and b. 47-48 C ardens almost absent ...... C. commersoni 13 b. small and blocky, sometimes with a C. latipinnis small posterior-directed projection or c. 49-50 C. latipinnis beak; anterior ends of mandibles (from ventral view of head) well posterior, 9 (1). Frontoparietal fontanelle (Fig. 7) much closer to posterior than anterior a. very narrow ‘lck of fontanelle length .. . ends of maxillae; anterior-dorsal C. platyrhynchus maxillary projections prominent and b. narrow, 25-28% of fontanelle length ... 10 pointed ...... C. discobolus c. moderately wide, 29-35% of fontanelle length ...... 12 13 (12). Number of vertebrae (including 4 for d. wide, 36-45% of fontanelle length ...... 14 Weberian complex) e. very wide, .45% of fontanelle length a. 44-46 C. commersoni (often over 60% and somewhat oval in b. 47-48 C. commersoni shape) ...... X. texanus C. latipinnis c. 49-50 C. latipinnis 10 (9). First (most anterior) interneural bone (Fig. 8) 14 (9). First (most anterior) interneural bone a. large and angular or anvil-shaped with a (Fig. 8) prominent posterior-directed projection a. large and fan-shaped across top X. texanus or beak; anterior ends of mandibles b. large and angular or anvil-shaped with (from ventral view of head) well anter- a prominent posterior-directed projec- ior, at least mid-distance between tion or beak C ardens

99 Species Account -- Catostomus ardens

Fig. 12. Catostomus ardens adult (from Miller 1952). Adult Diagnosis: Back without conspicuous predorsal keel. Caudal peduncle deep, about 8-10% of body length. Mouth inferior but well forward. Lips relatively small with papillae, without notches at outer corners; lower lip with deep medial cleft, lobes usually adjacent and not reaching a perpendicular from nostrils. No prominent cartilaginous ridge on anterior margin of lower jaw. Nodules of gill rakers slightly to unbranched. Scales relatively large. Dorsal fin membranes well pigmented. Fontanelle wide. Total length usually 25-35 cm, up to 65 cm. (Also, Table 8.) Reproduction: Non-guarding, open-substrate lithophil. Spring, usually late May to mid June, a18°C. Tributary streams, inlets, or rocky shoals near shore of lakes; sometimes over sand or gravel in water <60 cm deep. Observed in spawning aggregations of 400-500. Water- hardened eggs 2.9-3.2 mm diameter, demersal, initially adhesive. Young: Hatch in 8-9 days at 17°C. Swim-up 7-8 days Fig. 13. after hatching. Young mostly in spawning streams or Regional distribution of Catostomus ardens. near shore in shallow water. Observed to graze on filamentous algae or algae on fixed objects.

Table 8. Selected juvenile and adult meristics for Catostomus ardens. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers for exterior row of first arch, specimens >70 mm SL. Mean or modal values underlined if known and noteworthy, rare or questionable extremes in parentheses.

Character Original Literature Character Original Literature Dorsal Fin Rays - P: (10)11-12-13(14) 11-13 Dorsal Fin Rays - R: 2-5 Anal Fin Rays - P: 7-8 7 Anal Fin Rays - R: 2-4 Caudal Fin Rays - P: (17)18 Caudal Fin Rays - RD: (8)9-10-11 Pectoral Fin Rays: (14)15-17 Caudal Fin Rays - RV: (6)7-8-9 Pelvic Fin Rays: 10 Lateral Scales: (57-)62-68 54-60-70(-79) Vertebrae: 47-48 Gill Rakers: 28-31-34

Table 9. Size at apparent onset of selected developmental events for Catostomus ardens, as observed under low power magnification. P = principal rays; R = rudimentary rays; Scales are lateral series. Rare or questionable extremes in parentheses. Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm TL or Scales mm SL mm TL mm SL mm TL Hatched: (7)8-11 (7)8-11 Dorsal - P: 13-15 14-16 14-16 17-19 Eyes Pigmented: 9-10 or • 9-10 or • Anal - P: 14-15 16-18 15-17 17-19 Yolk Assimilated: 12-13 12-14 Caudal - P: 12-13 12-14 13-14 14-15 Finfold Absorbed: 19 23 Caudal - R: 14-15 15-17 19-20 23 Pectoral Fin Buds: (7) or • (7) or * Pectoral: 14-15 16-18 15-18 17-22 Pelvic Fin Buds: 13-15 14-16 Pelvic: 14-17 17-19 18-19 (19-)22 • before hatching Scales: 21-23 26-28 24-28 29-35

References: Andreasen and Barnes 1975, Baxter and Simon 1970, Jordan and Gilbert 1881, Jordan and Evermann 1896, La Rivers 1962, Lee et al. 1980, McConnell et al. 1957, Miller 1952, Miller and Smith 1981, Minckley 1973, Modde (F. C., pers. commun.), Sigler and Miller 1963, Sigler and Sigler 1987, Simon 1946, Simpson and Wallace 1978, Tyus et al. 1982.

100 Table 10. Size at developmental interval (left) and gut phase (right) transitions for Catostornus ardens. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses. Transition to mm SL mm TL Transition to mm SL mm TL 0 Flexion Mesolarva: 12-13 12-14 2 - 90 bend: 14-17 17-19 Postflexion Mesolarva: 13-14 14-15 3 - Full loop: 18-19 (19-)22-24 Metalarva: 15-17 17-19(20) 4 - Partial crossover: 20-22 26-27 Juvenile: 19-20 23 5 - Full cross over: 27-28 34-35

Table 11. Summary of morphometrics and myomere counts by developmental phase for Catostomus ardens. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded. Flexion Postflexion Protolarvae (N=10) Mesolarvae (N=5) Mesolarvae (N=12) Metalarvae (N=12) Juveniles (N=12) i±SD Range i±SD Range i± SD Range i±SD Range jr-±SD Range

SL, mm: 11 1 9 13 13 1 12 14 15 1 13 17 17 1 15 19 25 4 19 36 TL, mm: 11 1 9 14 13 1 12 15 16 2 14 19 21 2 17 23 32 6 24 45

Lengths %SL: AS to AE 2 0 2 3 2 1 1 4 4 1 3 5 6 1 4 8 7 1 6 8 PE 8 1 7 9 8 1 7 10 11 1 10 12 14 1 12 16 15 1 14 16 OP1 15 1 12 17 17 2 15 19 20 1 19 23 26 1 23 27 26 1 25 28 b 0P2 52 l 50 53 56 1 53 57 56 1 55 58 PY 75 2 72 78 70 2a 69 72 OPAF 41 19 22 67 25 1 22 26 28 2 25 31 41 7' 30 51 ODF 33 2 29 36 35 2 31 36 39 1 37 41 44 3' 42 47 OD 49 1° 47 50 50 1 49 52 49 1 48 51 ID 62 ld 60 63 65 1 64 67 65 1 64 66 PV 78 1 76 80 76 1 75 77 79 1 76 80 77 1 76 78 75 1 73 76 OA 79 79 79 77 1 76 78 76 1 74 78 IA 84 84 84 84 1 84 86 83 1 82 85 AFC 109 1 107 110 112 1c 111 114 116 1 114 118 PC 103 1 102 104 105 1 104 106 112 3 109 117 120 2 118 122 125 1 123 128 57 5 49 64 16 22 0 43 P1 5 3 1 8 10 1 8 11 11 1 9 13 14 2 12 17 20 2 15 22 P2 2 3 0 6 11 1 8 12 14 1 12 16 15 ld 14 16 19 1 18 20 24 2 21 26 C A 7 7 7 10 I 9 12 15 2 12 18 Depths %SL: at BPE 9 1 7 10 10 1 9 12 13 1 11 15 16 1 15 18 18 0 17 18 OP1 10 1 9 13 10 1 9 12 14 1 12 17 18 1 16 20 20 1 18 21 OD 11 1 10 12 9 1 8 9 12 2 9 15 17 1 16 20 20 1 16 22 BPV 5 1 4 6 5 0 5 6 7 1 6 9 10 1 912 12 1 10 14 AMPM 3 0 2 3 3 0 3 4 5 1 4 6 7 0 6 8 8 0 7 8 Max. Yolk 7 2 3 11 0 1 0 2 Widths %SL: at BPE 8 1 6 10 9 1 9 10 12 1 10 13 15 1 14 16 16 1 15 16 OP1 b 1 4 8 7 1 6 9 10 1 9 11 13 1 11 15 16 1 14 17 OD 7 1 5 9 5 0 5 6 7 1 510 12 1 913 15 1 12 17 BPV 3 0 3 4 3 0 3 4 5 1 4 6 6 1 5 7 8 1 610 AMPM 2 0 2 2 2 0 2 2 3 0 2 3 3 0 3 4 4 0 3 5 Max. Yolk 8 3 5 14 1 1 0 2

Myomeres: to PY 35 1 34 36 33 1° 32 33 OPAF 15 11 4 32 6 0 6 7 6 1 5 7 12 4' 6 17 b 0P2 21 l 19 22 21 1 20 22 22 Od 21 22 ODF 12 1 10 13 12 0 11 12 13 1 12 14 15 2' 13 16 d OD 18 1' 17 19 17 1 16 18 17 ld 16 18 PV 37 1 36 38 36 1 36 37 37 1 35 38 36 1 34 37 35 1 35 36 Total 46 1 45 47 46 1 45 47 46 1 45 48 45 1 43 47 46 ld 45 47 aN = 2; bN = 10; `N = 11; d1■1 = 5; `1■1 = 1.

101 _

MIANWEreritaratleffiefeff, (111/PF IIIIMILINIKIMILILIIIML

Fig. 14. Catostomus ardens protolarva, recently hatched, 10.5 mm SL, 10.8 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

11111", • ••• •• V,. 1 . • • • alb°

•

• .••.•••••••••••■•••••.•••••••• acter-tr-

Fig. 15. Catostomus ardens protolarva, 11,4 mm SL, 11.9 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

102

Fig. 16. Catostomus ardens flexion mesolarva, recently transformed, 12.2 mm SL, 12.8 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

Fig. 17. Catostomus ardens postflexion mesolarva, 14.2 mm SL, 15.7 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

103 •

An* • ; ..• • : ' • 7 ; : SI• . • • . . .

;. . • . —6 0

, •'

Fig. 18. Catostomus ardens metalarva, recently transformed, 15.9 mm SL, 18.7 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

Fig. 19. Catostomus ardens metalarva, 17.8 mm SL, 21.5 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

104 Fig. 20. Catostomus ardens juvenile, recently transformed, 21.8 mm SL, 26.9 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

Fig. 21. Catostomus ardens juvenile, 28.2 mm SL, 35.6 mm TL. Cultured in 1987 with stock from Bear Lake, Utah.

105 Fig. 22. Selected skeletal features of Catostomus Fig. 23. Selected skeletal features of Catostomus ardens, juvenile, 21.4 mm SL, 26.2 mm TL. Top -- ardens, juvenile, 39.5 mm SL, 45.4 mm TL. Top -- postcleithrum. Middle -- anterior-dorsal maxillary postcleithrum. Middle — anterior-dorsal maxillary projections. Bottom -- mandible position. projections. Bottom — mandible position.

106 Fig. 25. Frontoparietal fontanelle of Catostomus ardens. Top -- juvenile, 21.4 mm SL, 26.2 mm TL. Bottom -- juvenile, 39.5 mm SL, 45.4 mm TL.

Table 12. Dimensions of frontoparietal fontanelle for Catostornus ardens larvae >16 mm SL, early (YOY) juveniles, and yearling.

Max. Max. Width Specimens width length as %of mm SL n (mm) (mm) length

17-19 2 1.0-1.2 2.0-2.2 45-60 20-21 1 0.9 2.0 43 22-25 2 0.9-0.9 2.3-2.4 38-39 Catostomus ardens. Top -- Fig. 24. Interneurals of 26-34 3 1.0-1.0 2.3-2.4 42-43 postflexion mesolarva, 16.8 mm SL, 19.2 mm TL. 35-46 1 1.2 2.8 43 Middle -- juvenile, 21.4 mm SL, 26.2 mm TL. Bottom 76-81 0 -- juvenile, 39.5 mm SL, 45.4 mm TL.

107 Species Account -- Catostomus commersoni

Fig. 26. Catostomus commersoni (from Miller 1952).

Adult Diagnosis: Back without conspicuous predorsal keel. Caudal peduncle depth about 63-8.6% TL. Mouth inferior, no hard, prominent, cartilaginous ridges along inside of jaws. Lips relatively small, papillose, without notches at corners; lower lip wider than long with a deep median cleft, usually without rows of papillae spanning the two lobes. Dorsal fin not large and not falcate. Scales large. Gill rakers relatively few, somewhat knobbed. Peritoneum pale or lightly speckled. TL usually 30-50 cm, up to 64 cm. (Also, Table 13.) Reproduction: Non-guarding, open-substrate lithophil. April or May to August, 7-19°C, usually >10°C; mostly June to mid-July in the Upper Colorado River Basin. Frequently in large aggregations migrate to streams or lake shores to spawn in shallow water, usually <0.3 m, and moderate currents, mostly 30-49 cm/sec, over sand or gravel; often over riffles in streams. Water-hardened eggs 2.6-3.3 mm diameter, demersal, initially adhesive. Young: Hatch in 5-11 days at 18-10°C, remain in gravel Fig. 27. Regional distribution of Catostomus corn- 1-2 weeks, drift as late protolarvae and mesolarvae, mersoni. usually at night, and subsequently occupy low velocity shoreline areas, often over sand and gravel or in aquatic vegetation. Table 13. Selected juvenile and adult meristics for Catostomus commersoni. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers for exterior row of first arch, specimens >70 mm SL. Mean or modal values underlined if known and noteworthy; rare or questionable extremes in parentheses. Character Original Literature Character Original Literature Dorsal Fin Rays - P: 10-11-12(13) (9)10-13(15) Dorsal Fin Rays - R: 2-3-4(5) Anal Fin Rays - P: (.5-)7(8) (6)7-8 Anal Fin Rays - R 2- Caudal Fin Rays - P: 18 18 Caudal Fin Rays - RD: 10711-13 Pectoral Fin Rays: 13-15-16(17) 13-19 Caudal Fin Rays - RV: 8-10 Pelvic Fin Rays: 8-10 9-11 Lateral Scales: 36-59-68-72 53-56-70-76(85) Vertebrae: 45716-48 44-48 Gill Rakers: 20-27

Table 14. Size at apparent onset of selected developmental events for Catostomus commersoni, as observed under low power magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses.

Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm TL or Scales mm SL mm TL mm SL mm

I latched: (7)8-10 8-10 Dorsal - P: 12-13 14 14-16 16-17 Eyes Pigmented: (7)8 or * 8 or • Anal - P: 14-16 16-17 15-16(17) 18-19(20) Yolk Assimilated: 10-12(44) (10)11-13(-15) Caudal - P: 10-12 10-13 (12)13-15 (13)14-16 Finfold Absorbed: (17-)19-20 (21-)23-24 Caudal - R: 13-15 14-16 (17)18 (21)22-23 Pectoral Fin Buds: (7)8 or * 8 or • Pectoral: 14-16 16-17 16(-20) 19(-24) Pelvic Fin Buds: 13-15 (14)15-16 Pelvic: 15-16 18-19 16-18 19-22 • before hatching Scales: 22(23) 27 29-31 36-37

References: Auer 1982, Baxter and Simon 1970, Beckman 1952, Carlander 1969, Carlson et al. 1979, Ellis 1914, Fuiman 1979, Fuiman and Trojnar 1980, Geen et al. 1966, Hubbs et al. 1943, Jones et al. 1978, Jordan and Evermann 1896, Lippson and Moran 1974, Miller 1952, Minckley 1973, Prewitt 1977, Reighard 1920, Scott and Crossman 1973, Smith 1985, Stewart 1927, Twomey et al. 1984, Woodling 1985. 108 Table 15. Size at developmental interval (left) and gut phase (right) transitions for Catostomus commersoni. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses.

Transition to mm SL mm TL Transition to mm SL mm TL

Flexion Mesolarva: 10-12 10-13 2 - 90° bend: 14-15(16) (16)17(18) Postflexion Mesolarva: (12)13-15 (13)14-16 3 - Full loop: (16)17-18 (19)20-21(22) Metalarva: 15-16(17) 18-19(20) 4 - Partial crossover: 19-20(21) (22)23-24(-26) Juvenile: (17-)19-20 (21-)23-24 5 - Full cross over: (20)21-25 (24)25-30(31)

Table 16. Summary of morphometrics and myomere counts by developmental phase for Catostomus commersoni. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded.

Flexion Postflexion Protolarvae (N=11) Mesolarvae (N=16) Mesolarvae (N=9) Metalarvae (N=18) Juveniles (N=25) SD Range ,V±- SD Range :f ± SD Range /± SD Range ±SD Range

SL, mm: 10 1 8 12 12 2 10 15 14 1 12 16 17 1 15 20 25 6 19 39 TL, mm: 10 1 9 12 13 2 10 16 16 2 14 19 21 2 18 24 30 7 23 48

Lengths %SL: AS to AE 2 0 2 3 2 1 2 3 4 1 2 6 6 1 4 8 8 1 610 PE 8 1 8 9 8 1 7 10 11 1 9 14 14 1 12 15 15 1 13 16 OP1 16 1 13 19 18 1 16 20 22 2 19 25 26 2 20 30 28 1 24 29 b 0P2 53 l 52 54 56 2 54 59 57 2 52 59 PY 70 12 47 80 63 10' 50 75 OPAF 31 15 22 73 25 1 23 27 30 2 25 33 48 10 32 68 ODF 37 2 34 42 38 2 35 43 44 3' 38 48 OD 50 lb 49 51 51 1 48 53 51 1 48 53 ID 63 ld 61 64 65 2 61 67 65 1 61 68 PV 78 2 76 82 79 1 76 81 80 1 78 81 77 1 75 79 76 1 72 78 OA 80 ld 79 80 78 1 76 79 77 1 73 79 IA 85 ld 84 86 85 1 83 86 84 1 79 86 AFC 110 2 108 113 113 2 110 119 115 1 113 117 PC 104 1 101 106 106 1 104 109 114 4 109 120 121 2 116 126 122 1 119 124 51 13 26 63 18 21 0 50 P1 7 4 2 12 11 1 10 12 12 1 11 14 15 2` 12 19 17 1 15 20 P2 2 2 0 6 9 3 4 16 12 1 10 15 17 ld 16 17 19 2 15 22 20 1 18 24 A 7 Od 7 7 11 2 7 14 13 2 10 16

Depths %SL: at BPE 9 1 7 11 10 1 9 11 13 1 11 15 16 1 14 19 17 1 16 19 OP1 11 1 9 12 11 1 10 13 16 2 14 18 18 1 16 20 20 1 18 22 OD 10 2 8 13 9 1 8 10 12 2 9 16 16 2 13 20 19 1 17 22 BPV 5 1 3 6 5 0 5 6 7 1 6 9 9 1 711 11 1 10 14 AMPM 3 1 2 3 4 0 3 4 5 1 4 7 7 1 5 8 8 1 7 9 Max. Yolk 6 3 1 11 1 1 0 3

Widths %SL: at BPE 9 2 7 11 10 1 9 12 13 1 11 15 15 1 13 17 16 1 14 18 OP1 6 1 5 7 7 1 6 8 10 1 8 12 13 1 11 14 16 2 13 20 OD 6 1 5 9 5 0 5 6 7 1 5 9 10 2 814 13 2 10 16 BPV 4 0 3 4 4 0 3 4 5 1 4 6 6 1 4 8 8 1 710 AMPM 2 0 2 2 2 0 2 2 3 0 2 3 3 1 2 4 4 0 4 5 Max. Yolk 6 3 1 10 1 2 0 4

Myomeres: to PY 33 7 18 38 28 6a 21 35 OPAF 9 7 4 30 6 1 5 8 6 1b 5 8 16 6 728 0P2 21 l 19 22 21 1 20 23 21 lf 20 22 a ODF 13 1 12 14 14 1 12 17 15 2d 12 17 14 2 11 17 OD 19 lb 17 20 17 be 16 19 17 lf 16 18 f PV 38 2 35 40 37 2 34 40 38 1 36 40 35 1 34 37 35 l 33 36 f Total 47 1 44 48 46 1 43 48 46 1 45 49 45 1 44 47 45 l 43 47

c d -; e f aN 8; bN 7; N 8; N N = 17; N = 20.

109 Fig. 28. Catostomus commersoni protolarva, recently hatched, 7.8 mm SL, 8.0 mm TL (from Stewart 1926).

Fig. 29. Catostomus commersoni protolarva, 10.5 mm SL, 10.7 mm TL (from Fuiman 1979).

110 Fig. 30. Catostomus commersoni flexion mesolarva, recently transformed, 12.8 mm SL, 13.4 mm TL. Collected in 1977 from the Yampa River, Colorado.

-.AO& IRAVADE 11" TAREGRAFFEEREARAREARIREFEREELFEZER. 71NA 11

Fig. 31. Catostomus commersoni postflexion mesolarva, 16.3 mm SL, 18.2 mm TL (from Fuiman 1979).

111 Fig. 32. Catostomus commersoni metalarva, recently transformed, 17.8 mm SL, 20.4 mm TL (from Buynak and Mohr 1978).

Fig. 33. Catostomus commersoni metalarva, 19.8 mm SL, 23.8 mm TL (from Buynak and Mohr 1978).

112 Fig. 34. Catostomus commersoni juvenile, recently transformed, 21.3 mm SL, 25.8 mm TL (from Fuiman 1979).

Fig. 35. Catostomus commersoni juvenile, 30.8 mm SL, 37.9 mm TL. Collected in 1977 from the Yampa River, Colorado.

113 Fig. 36. Selected skeletal features of Catostomus Fig. 37. Selected skeletal features of Catostomus commersoni, juvenile, 20.4 mm SL, 25.0 mm TL. Top commersoni, juvenile, 42.6 mm SL, 52.5 mm TL. postcleithrum. Middle -- anterior-dorsal maxillary Top — postcleithrum. Middle -- anterior-dorsal maxil- projections. Bottom -- mandible position. lary projections. Bottom -- mandible position.

114 Fig. 39. Frontoparietal fontanelle of Catostomus commersoni. Top -- juvenile, 28.0 mm SL, 34.8 mm TL. Bottom -- juvenile, 39.8 mm SL, 49.0 mm TL.

Table 17. Dimensions of frontoparietal fontanelle for Catostomus commersoni larvae >16 mm SL, early (YOY) juveniles, and yearling. Max. Max. Width Specimens width length as %of mm SL n (mm) (mm) length 17-19 2 0.8-1.0 2.0-2.2 40-45 20-21 2 0.6-0.8 1.9-2.1 32-38 Fig. 38. Interneurals of Catostomus commersoni. 22-25 1 0.8 2.0 40 Top -- postflexion mesolarva, 14.7 mm SL, 17.0 mm 26-34 2 0.8-0.8 2.3-2.6 31-35 TL. Middle -- juvenile, 20.4 mm SL, 25.0 mm TL. 35-46 1 0.9 3.0 30 Bottom -- juvenile, 42.6 mm SL, 52.5 mm TL. 76-81 1 0.8 3.1 26

115 Species Account -- Catostomus discobolus

wm.o.wm WYOMING .COLORADO

Fig. 40. Catostomus discobolus adult (Miller 1952).

Adult Diagnosis: No conspicuous predorsal keel. Caudal peduncle slender to deep, 3.2-10% SL, often correlated with habitat. Mouth inferior and well back. Hard, truncate, cartilaginous ridges along inside of jaws, especially prominent on lower jaw. Lips large with notches at outer corners, papillose except on outer face of upper lip; lower lip with shallow cleft, lobes broadly connected by 3 or more rows of papillae usually concen- tric with the anterior margin of the lip. Fontanelle typically closed. Pelvic axillary process absent or a simple fold. Interradial membranes of caudal fin well pigmented. Peritoneum black to dusky. TL usually 25- 35 cm, up to 40 cm. (Also, Table 18.) Reproduction: Non-guarding, open-substrate lithophil. May to September, usually June and July, at 15-18°C (possibly also in fall and/or winter in Little Colorado River based on collection of larvae). Water-hardened eggs 3.3-33 mm diameter, demersal, initially adhesive. Young: Later stage protolarvae and mesolarvae drift, Fig. 41. Regional distribution of Catostomus disco- predominately at night. Young typically occupy slow, bolus. shallow waters, often <03 m, near shore and in backwaters; sometimes trapped in cut-off pools or channels. Often associated with juveniles of other species. Table 18. Selected juvenile and adult meristics for Catostomus discobolus. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers for exterior row of first arch, specimens >70 mm SL Mean or modal values underlined if known and noteworthy; rare or questionable extremes in parentheses. Character Original Literature Character Original Literature Dorsal Fin Rays - P: (9)10-11(12) 9-1011-12 Dorsal Fin Rays - R: 2- Anal Fin Rays - P: 7 7(8) Anal Fin Rays - R: 2(3) Caudal Fin Rays - P: (17)18 Caudal Fin Rays - RD: (10)11-12 Pectoral Fin Rays: 14-15-16 Caudal Fin Rays - RV: 9-10(11) Pelvic Fin Rays: 8-9-10 (7)8-9-10(11) Lateral Scales: (78-)86-115(-122) Vertebrae: 47=49 45-47-49-50 Gill Rakers: 28-35-44

Table 19. Size at apparent onset of selected developmental events for Catostomus discobolus, as observed under low power magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses. Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm II or Scales mm SL mm TL mm SL mm TL

Hatched: (8)9-10(11) (8)9-11 Dorsal - P: (11-)13 (12-)14 (14)15 (16)17-18 Eyes Pigmented: 9-10 or ' (9)10 or ' Anal - P: 14-15 16-17 (16)17 (19)20 Yolk Assimilated: (10-)12-13 (11)12-14 Caudal - P: 10-12 11-12(13) (11)12-13 (12)13-14 Finfold Absorbed: 21-22(23) 26-27(28) Caudal - R: 14 15 19-20 23-25 Pectoral Fin Buds: (8) or " (8) or * Pectoral: 14-15 16-17 16-18(19) 18-21(23) Pelvic Fin Buds: 14 (15)16 Pelvic: 16 18-19 19-20 23-25 ' before hatching Scales: 28-34 (34)35-42 30-39 36-48

References: Andreasen and Barnes 1975, Baxter and Simon 1970, Beckman 1952, Behnke et al. 1982, Carlson et al. 1979, Cope 1872, Holden 1973, Hubbs and Hubbs 1947, Hubbs et al. 1943, Jordan and Evermann 1896, Lee et al. 1980, McAda 1977, Miller 1952, Minckley 1973, Prewitt 1977, Sigler and Miller 1963, Smith 1966, Tyus et al. 1982, Vanicek 1967, Woodling 1985.

116 Table 20. Size at developmental interval (left) and gut phase (right) transitions for Catostomus discobolus. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses.

Transition to mm SL mm TL Transition to mm SL mm TL

Flexion Mesolarva: 10-12 11-12(13) 2 - 90° bend: 14(15) 15-16(17) Postflexion Mesolarva: (11)12-13 (12)13-14 3 - Full loop: 15(16) 17-18 Metalarva: (16)17 (19)20 4 - Partial crossover: (16)17 18-20 Juvenile: 21-22(23) 26-27(28) 5 - Full cross over (16)17-19(-21) (18)19-23(-25)

Table 21. Summary of morphometrics and myomere counts by developmental phase for Catostomus discobolus. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded.

Flexion Postflexion Protolarvae (N=6) Mesolarvae (N=7) Mesolarvae (N=16) Metalarvae (N=22) Juveniles (N=16) SD Range Y±SD Range ±- SD Range .V±SD- Range i-±SD Range

SL, mm: 11 1 10 12 12 1 10 13 15 2 11 17 19 2 17 22 28 6 21 40 TL, mm: 11 1 10 12 13 1 11 14 16 2 12 20 23 2 20 28 34 8 26 50

Lengths %SL: AS to AE 2 0 2 2 3 1 2 4 5 1 3 6 7 1 5 8 8 1 6 9 PE 7 0 6 7 9 1 8 10 11 1 9 13 13 1 12 15 14 1 12 16 OP1 14 1 13 15 18 1 17 19 22 2 19 25 25 1 24 27 25 1 23 27 0P2 55 1h 53 57 58 2 55 61 58 1 56 60 PY 78 1 77 79 68 12a 50 74 OPAF 40 14 29 62 26 5 22 37 32 4 26 40 54 10 42 70 ODF 34 6 27 43 39 3 36 43 46 2` 43 49 OD 51 1d 49 53 52 1 49 54 51 1 47 54 ID 62 le 61 64 64 1 63 66 64 1 62 66 PV 80 0 79 81 77 2 74 79 79 1 76 81 76 1 75 78 75 1 72 76 OA 78 If 76 80 77 1 76 78 76 1 73 77 IA 83 lf 82 85 84 1 82 86 83 1 81 84 AFC 110 1g 107 112 114 1 112 115 115 1 113 116 PC 104 1 103 104 106 1 105 107 113 3 109 116 121 2 116 124 123 1 120 124 Y 63 3 61 67 26 26 053 P1 5 1 3 6 10 1 9 11 12 1 11 13 15 1 13 19 18 1 15 20 P2 2 2 0 5 9 2 5 11 13 1 11 15 D 15 2h 11 17 19 1 17 21 21 1 19 23 A 7 lf 6 8 11 2 8 13 14 1 12 16

Depths %SL: at BPE 8 1 6 9 11 1 9 11 13 2 11 15 15 1 14 16 16 1 14 17 OP1 10 1 9 13 12 1 11 13 15 2 12 17 19 1 16 21 19 1 18 21 OD 14 2 12 17 10 1 9 12 11 3 8 17 17 2 14 20 19 1 16 21 BPV 5 1 4 6 6 0 5 6 7 1 5 8 10 1 911 11 1 10 14 AMPM 2 0 2 3 3 0 3 4 5 1 4 6 7 0 6 7 7 0 7 9 Max. Yolk 10 2 7 12 3 3 0 7

Widths %SL: at BPE 8 1 6 9 10 0 10 11 12 1 10 14 15 1 14 16 15 1 14 16 OP1 6 1 4 7 8 0 7 9 10 2 8 13 14 1 13 17 16 1 15 18 OD 10 1 8 12 6 0 5 6 7 2 6 10 12 2 9 15 15 1 12 17 BPV 3 1 3 5 4 0 3 5 5 1 4 6 6 1 5 7 8 1 6 9 AMPM 2 0 1 2 2 0 2 2 2 0 1 3 3 0 2 3 3 1 2 4 Max. Yolk 12 2 10 15 4 4 0 8 Myomeres: to PY 38 1 37 39 34 r 23 37 OPAF 16 7 10 27 7 4 5 15 8 1 6 12 20 7 11 33 0P2 23 lf 21 25 24 1 20 26 23 1` 22 24 ODF 13 3 8 18 15 1 14 18 18 2` 15 20 OD 19 2h 17 22 19 1 17 21 18 Oe 18 19 PV 39 1 39 40 39 1 37 40 39 1 38 39 37 1 35 38 36 le 35 38 Total 48 1 47 48 48 1 47 49 48 0 48 49 47 1 47 48 48 le 47 48

= 4; hIsl = 10; "NI = 9; dN = 14; eN = 8; fN = 7; gN = 15; hN = 13.

117

Fig. 42. Catostomus discobolus protolarva, recently hatched, 10.5 mm SL, 11.1 mm TL. Cultured in 1978 with stock from the White River, Colorado.

, 1 44 4 11 a ( 41 41. 41 * 44. 14 .0 . 4 tieW W It•Vit;;WV* WIrdlat • e e W Ww. W we

-ww—•444 z

Fig. 43. Catostomus discobolus protolarva, 12.0 mm SL, 12.5 mm TL. Cultured in 1978 with stock from the White River, Colorado.

118 Fig. 44. Catostomus discobolus flexion mesolarva, recently transformed, 13.2 mm SL, 14.1 mm TL. Collected in 1978 from the White River, Colorado.

.411; ,

Fig. 45. Catostomus discobolus postflexion mesolarva, 14.3 mm SL, 16.4 mm TL. Collected in 1976 from the White River, Colorado. 119 Fig. 46. Catostomus discobolus metalarva, recently transformed, 15.4 mm SL, 18.2 mm TL. Collected in 1976 from the White River, Colorado.

Fig. 47. Catostomus discobolus metalarva, 18.1 mm SL, 21.8 mm TL. Collected in 1976 from the White River, Colorado.

120 Fig. 48. Catostomus discobolus juvenile, recently transformed, 22.7 mm SL, 27.3 mm TL. Collected in 1976 from the White River, Colorado.

Fig. 49. Catostomus discobolus juvenile, 31.8 mm SL, 38.0 mm TL. Collected in 1976 from the White River, Colorado.

121 Fig. 50. Selected skeletal features of Catostomus Fig. 51. Selected skeletal features of Catostomus discobolus, metalarva, 21.8 mm SL, 25.5 mm TL. discobolus, juvenile, 43.0 mm SL, 52.5 mm TL. Top -- postcleithrum. Middle — anterior-dorsal Top — postcleithrum. Middle — anterior-dorsal maxil- maxillary projections. Bottom — mandible position. lary projections. Bottom mandible position.

122 Fig. 53. Frontoparietal fontanelle of Catostomus discobolus. Top — juvenile, 27.1 mm SL, 32.5 mm TL. Bottom -- juvenile, 32.4 mm SL, 38.5 mm TL.

Table 22. Dimensions of frontoparietal fontanelle for Catostotnus discobolus larvae > 16 mm SL, early (YOY) juveniles, and yearling.

Max. Max. Width Specimens width length as % of mm SL n (mm) (mm) length

17-19 4 0.6-0.9 1.4-1.8 41-50 20-21 2 0.5-0.9 1.7-1.7 29-35 22-25 3 0.5-0.8 1.3-2.8 29-38 Fig. 52. Interneurals of Catostomus discobolus. Top 0.6-0.7 27-35 postflexion mesolarva, 15.3 mm SL, 17.0 mm TL. 26-34 2 2.0-2.2 Middle -- metalarva, 21.8 mm SL, 25.5 mm TL. 35-46 1 0.7 2.7 26 0.7 3.7 19 Bottom -- juvenile, 43.0 mm SL, 52.5 mm TL. 76-81 1

123 Species Account -- Catostomus latipinnis

MI a Cargo WYOMING

COLORADO

Fig. 54. Catostomus latipinnis adult (Miller 1952).

Adult Diagnosis: Back without conspicuous predorsal keel. Caudal peduncle slender, typically .s6% SL. Mouth inferior, moderate in size; no hard, prominent, cartilaginous ridges along inside of jaws. Lips large, fleshy, profusely papillose, without notches at corners; \ lower lip with a deep median cleft allowing one or no rows of papillae to span the two lobes; lobes extend beyond vertical from nostrils, often to eyes. Dorsal fin large and falcate. Scales small. Fontanelle present. TL usually 30-40 cm, up to 60 cm. (Also, Table 23.) Reproduction: Non-guarding, open-substrate lithophil. April to August, mostly May to early July, 6 to at least 13°C. Usually over gravel-cobble bars or riffles, or coarse gravel under <1.2 m of water. May or may not migrate to spawning grounds. Water-hardened eggs 3.8- 3.9 mm diameter, demersal, initially adhesive. MEXICO Young: Larvae, predominately mesolarvae, drift, mostly at night. Young typically occupy slow to quiet and shallow waters along shore and in backwaters or pools; Fig. 55. Regional distribution of Catostomus lati- often in the marginal areas of swift-flowing streams; not pinnis. common in sluggish, very warm areas.

Table 23. Selected juvenile and adult meristics for Catostomus latipinnis. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers for exterior row of first arch, specimens >70 mm SL. Mean or modal values underlined if known and noteworthy; rare or questionable extremes in parentheses.

Character Original Literature Character Original Literature Dorsal Fin Rays - P: (11)12-13(14) (10)11-12-13-14(15) Dorsal Fin Rays - R 3- Anal Fin Rays - P: 7 7(8) Anal Fin Rays - R (1)2-3 Caudal Fin Rays - P: 18 Caudal Fin Rays - RD: 10-11-14 Pectoral Fin Rays: 15-h-17 18 Caudal Fin Rays - RV: 9-10-11 Pelvic Fin Rays: (9)10(11) 9-12-11 Lateral Scales: 89-98-105-116(-120) Vertebrae: 47-50 Gill Rakers: 25-27-31-32(-35)

Table 24. Size at apparent onset of selected developmental events for Catostomus latipinnis, as observed under low power magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses.

Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm TL or Scales mm SL mm TL mm SL mm TL Hatched: (8-)10-11 (8-)10-11 Dorsal - P: 15 16 17-18 20-22 Eyes Pigmented: (9)10 or • (9)10 or * Anal - P: 17 18-19 19-20(21) 23-24 Yolk Assimilated: 15 16-17 Caudal - P: 13 13(14) 15 16 Finfold Absorbed: 23-24(25) 28-29(31) Caudal - R (16)17 18(19) 23 28-29 Pectoral Fin Buds: (9) or * (9) or • Pectoral: 17 18-19 19-22 22-27 Pelvic Fin Buds: (15)16(17) 17-18 Pelvic: 17-18 19-20 23 (28)29 * before hatching Scales: (36)37-39 (44)45-49 39-42 48-51

References: Baird and Girard 1854, Behnke et al. 1982, Beckman 1952, Carlson et al. 1979, Holden 1973, Hubbs and Hubbs 1947, Hubbs and Miller 1953, Hubbs et al. 1943, Jordan and Evermann 1896, Joseph et al. 1977, La Rivers 1962, Lee et al. 1980, McAda 1977, Miller 1952, Minckley 1973, Prewitt 1977, Sigler and Miller 1963, Tyus et al. 1982, Woodling 1985.

124 Table 25. Size at developmental interval (left) and gut phase (right) transitions for Catostomus latipinnis. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses.

Transition to mm SL mm TL Transition to mm SL mm TL 0 Flexion Mesolarva: 13 13(14) 2 - 90 bend: (17)18(-20) (20)21(-24) Postflexion Mesolarva: 15 16 3 - Full loop: (19-)21-25(-27) (23-)26-30(-33) Metalarva: 19-20(21) 23-24 4 - Partial crossover: (22)23-32(-37) (27)28-39(46) Juvenile: 23-24(25) 28-29(-31) 5 - Full cross over: (29-)35-42 (36-)40-51

Table 26. Summary of morphometrics and myomere counts by developmental phase for Catostonzus latipinnis. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded.

Flexion Postflexion Protolarvae (N=9) Mesolarvae (N=10) Mesolarvae (N=20) Metalarvae (N=15) Juveniles (N=19) Y±- SD Range Tc±- SD Range Y±- SD Range ± SD Range Y±- SD Range

SL, mm: 11 1 10 13 14 1 13 15 18 1 15 20 22 1 20 25 32 6 23 43 TL, mm: 12 1 11 13 14 I 14 16 20 2 16 24 27 2' 24 31 40 7 29 53

Lengths %SL: AS to AE 2 0 2 3 3 1 3 4 6 1 3 7 7 1 6 8 8 1 710 PE 7 1 6 9 9 1 8 10 12 1 9 14 13 1 12 14 14 1 13 15 OP1 14 1 12 16 18 1 16 19 23 2 19 27 26 1 24 28 25 1 24 28 0P2 53 la 50 54 55 1 52 57 55 1 52 57 PY 78 2 75 81 69 9 48 75 50 b 50 50 OPAF 54 19 32 77 26 3 22 32 34 5` 27 44 55 11 34 67 ODF 35 2 33 38 38 2 35 40 44 3" 36 48 45 0' 45 45 OD 50 l a 49 51 49 1 47 51 48 1 46 49 ID 64 le 62 67 65 1 62 67 65 1 61 66 PV 79 1 77 81 77 1 75 78 78 1 76 80 75 2 74 78 74 1 72 76 OA 78 lf 76 80 75 1 74 78 75 1 72 77 IA 84 1g 83 84 82 1 81 84 82 1 80 85 AFC 110 1 108 112 113 1 111 114 114 li 112 116 PC 103 1 102 105 105 1 104 107 115 4 109 123 122 2h 117 125 123 1 121 125 Y 61 5 54 67 46 9 23 54 0 2 0 7 P1 6 2 3 9 11 1 9 12 12 1 10 15 16 1 14 18 18 1 16 19 P2 4 2 0 7 11 2 9 13 14 1 11 15 D 18 2a 15 21 22 1 20 24 24 1 23 26 A 8 l d 5 9 12 2 9 14 14 1 12 16

Depths %SL: at BPE 8 1 7 9 10 1 9 11 13 1 11 16 16 1 15 17 16 1 15 17 OP1 9 1 8 10 11 1 10 12 16 2 13 18 19 1 16 21 19 1 17 22 OD 14 1 13 15 11 1 9 13 14 3` 10 19 19 2 16 22 19 1 17 22 BPV 5 1 4 6 6 0 5 6 8 1 6 10 11 1 9 12 11 1 10 13 AMPM 3 1 2 3 3 0 3 4 6 1 4 7 7 0 6 8 7 0 7 8 Max. Yolk 12 3 9 16 5 2 2 8 0 0 0 1

Widths %SL: at BPE 8 1 6 9 10 1 9 12 13 1 10 15 16 1 14 17 15 1 15 17 OP1 7 1 6 9 7 1 6 8 11 1 8 13 14 1 13 16 16 1 14 17 OD 10 1 7 11 6 1 5 8 8 2 6 12 12 1 10 15 13 2 11 17 BPV 3 0 3 4 4 1 4 6 6 1 4 8 7 1 6 8 8 1 6 9 AMPM 2 0 1 2 2 0 1 2 3 0 2 3 4 0 3 4 4 0 3 5 Max. Yolk 13 3 9 18 6 3 1 9 0 0 0 1

Myomeres: to PY 38 1 37 39 34 5 22 38 21 b 21 21 OPAF 23 11 10 37 7 2 5 10 9 3' 6 15 22 8` 9 32 0P2 21 la 19 23 22 le 21 24 22 1k 21 23 ODF 12 2 10 15 13 1 12 15 15 1h 12 17 15 1' 14 15 k OD 18 la 17 21 18 le 16 19 18 l 17 19 PV 39 1 38 40 39 1 38 40 39 1 37 40 37 le 36 38 37 lk 36 38 Total 48 1 47 49 48 1 47 49 48 1 47 49 47 le 46 48 48 lk 47 48 aN = 17; hN = 1; eN = 19; "N = 12; eN = 14; tIs/ = 15; gN = 7; hN = 13; 'N = 2; iN = 18; kN = 9

125

frk- A

Fig. 56. Catostomus latipinnis protolarva, recently hatched, 10.3 mm SL, 10.6 mm TL. Cultured in 1978 with stock from the Yampa River, Colorado.

• • • • ,„ * • • • • •• *P ..• •,**6••■•■ •...... • • • • • v...... •••• • • ••• • • • • • 1 •• • • * • • .• .• • , _ 0 IA •••••••••• • •• • • •• • • •••• • • . ! • ." • . .

71g. 57. Catostomus latipinnis protolarva, 12.4 Mal SL, 12.9 mm TL. Cultured in 1978 with stock from the Yampa River, Colorado.

126

•

Fig. 58. Catostomus latipinnis flexion mesolarva, recently transformed, 13.0 mm SL, 14.0 mm TL. Cultured in 1978 with stock from the Yampa River, Colorado.

• • .• ...... •

•

Fig. 59. Catostomus latipinnis postflexion mesolarva, 16.8 mm SL, 18.9 mm TL. Collected in 1976 from the White River, Colorado.

127 Fig. 60. Catostomus latipinnis metalarva, recently transformed, 20.5 mm SL, 24.5 mm TL. Collected in 1976 from the White River, Colorado.

Fig. 61. Catostomus latipinnis metalarva, 22.7 mm SL, 27.5 mm TL. Collected in 1976 from the White River, Colorado.

128 Fig. 62. Catostomus latipinnis jvvenile, recently transformed, 26.6 mm SL, 32.0 mm TL. Collected in 1976 from the White River, Colorado.

Fig. 63. Catostomus latipinnis juvenile, 31.6 mm SL, 38.0 mm TL. Collected in 1976 from the White River, Colorado.

129 a

Fig. 64. Selected skeletal features of Catostomus Fig. 65. Selected skeletal features of Catostomus latipinnis, metalarva, 24.6 mm SL, 29.0 mm TL. latipinnis, juvenile, 42.1 mm SL, 52.0 mm TL. Top — postcleithrum. Middle — anterior-dorsal maxil- Top — postcleithrum. Middle -- anterior-dorsal maxillary projections. Bottom -- mandible position. lary projections. Bottom — mandible position.

130 Fig. 67. Frontoparietal fontanelle of Catostomus latipinnis. Top metalarva, 24.6 mm SL, 29.0 mm TL. Bottom — juvenile, 33.1 mm SL, 41.0 mm TL.

Table 27. Dimensions of frontoparietal fontanelle for Catostomus latipinnis larvae >16 mm SL, early (YOY) juveniles, and yearling.

Max. Max. Width Specimens width length as % of mm SL n (mm) (mm) length

17-19 3 0.8-1.2 1.2-2.0 50-67 20-21 3 0.6-0.7 1.8-2.0 33-35 22-25 3 0.8-0.8 1.8-2.1 38-44 Fig. 66. Interneurals of Catostomus latipinnis. Top-- 26-34 2 0.7-0.8 2.2-2.3 30-36 postflexion mesolarva, 14.7 mm SL, 17.0 mm TL. 35-46 1 0.7 2.3 30 Middle metalarva, 24.6 mm SL, 29.0 mm TL. 76-81 1 1.0 4.0 25 Bottom juvenile, 42.1 mm SL, 52.0 mm TL.

131 Species Account -- Catostomus platyrhynchus

, ,4 -.4211/P ._04 R444).;\ ,667

Fig. 68. Catostomus platyrhynchus adult (Miller 1952).

Adult Diagnosis: Back without conspicuous predorsal keel. Caudal peduncle deep, 8-10% SL. Mouth inferior and well back. Lips large with notches at outer corners, papillose except on outer face of upper lip and antero- lateral corners of lower lip; lower lip with shallow cleft, lobes broadly connected by 3-5 rows of papillae in a convex arch. Prominent, truncate cartilaginous ridge on anterior margin of lower jaw. Fontanelle narrow, rarely closed. Pelvic wdllary process well developed. Inter- radial membranes of caudal fin with little or no pigment. Peritoneum black to dusky. TL up to 25 cm. (Also, Table 28.) Reproduction: Non-guarding, open-substrate lithophil. Short period during May to mid-August, 11-19'C. Resi- dent or tributary streams over gravel riffles, often adjacent to pools of swift mountain streams. Water- hardened eggs 2.3-2.7 mm diameter, demersal, initially adhesive. Young: Hatch in 7-8 days at about 18°C. Young in Fig. 69. Regional distribution of Catostomus platy- streams, occasionally drift into lakes; often found in rhynchus. cover in shallow water of moderate current. Larger young often associated with aquatic plants in quiet backwaters, pools, eddies and intermittent side channels. Specimens <30 mm TL feed largely on invertebrates. Table 28. Selected juvenile and adult meristics for Catostomus platyrhynchus. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Four added to vertebral count for Weberian complex. Scales are lateral series or line when complete. Gill rakers for exterior row of first arch, specimens >70 mm SL Mean or modal values underlined if known and noteworthy; rare or questionable extremes in parentheses.

Character Original Literature Character Original Literature Dorsal Fin Rays - P: 9-10-11 (8)9-10-12(13) Dorsal Fin Rays - R: (1)2-4 Anal Fin Rays - P: (6)7 7 Anal Fin Rays - R 2-3 Caudal Fin Rays - P: (17)18 Caudal Fin Rays - RD: (9-)11-12 Pectoral Fin Rays: 14-15-16 15 Caudal Fin Rays - RV: (7)8-9(11) Pelvic Fin Rays: 9-10 8-9-10 Lateral Scales: 76-86 (60-)75-97(-108) Vertebrae: 46-48(50) 42:44-47(48) Gill Rakers: 23-37

Table 29. Size at apparent onset of selected developmental events for Catostomus platyrhynchus, as observed under low power magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses.

Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm TL or Scales mm SL mm TL mm SL mm TL Hatched: (7)8 (7)8 Dorsal - P: 13 14 14-17 16-19 Eyes Pigmented: 8 8 Anal - P: 14-15 16-17 16-17 18-19 Yolk Assimilated: (10)11 (10)11-12 Caudal - P: 11 11-12 13-14 15 Finfold Absorbed: 21-22 25-27 Caudal - R: 14 15-16 20-21 24-25 Pectoral Fin Buds: (7) or * (7) or * Pectoral: 13-15 15-17 18-20 22-23 Pelvic Fin Buds: 13 14-15 Pelvic: 16 18 18-20 22-23 * before hatching Scales: 23-24 28-30 32-38 38-45

References: Baxter and Simon 1970, Beckman 1952, Behnke et al. 1982, Cope 1872, Hauser 1969, Hubbs et al. 1943, Jordan and Evermann 18%, Lee et al. 1980, Moyle 1976, Rutter 1903, Scott and Crossman 1973, Sigler and Miller 1963, Sigler and Sigler 1987., Simpson and Wallace 1978, Smith 1966, Tyus et al. 1982, Woodling 1985, Wydoski and Whitney 1979. 132 Table 30. Size at developmental interval (left) and gut phase (right) transitions for Catostomus platyrhynclu4s. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses.

Transition to mm SL mm T1. Transition to mm SL mm TL

Flexion Mesolarva: 11 11-12 2 - 90° bend: 14-17 16-19 Postflexion Mesolarva: 13-14 15 3 - Full loop: 16-17 18-21 Metalarva: 16-17 18-19 4 - Partial crossover: 18-20 22-24 Juvenile: 21-22 25-27 5 - Full cross over: 21-23 25-28

Table 31. Summary of morphometrics and myomere counts by developmental phase for Catostomus platyrhynchus. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded.

Flexion Postflexion Protolarvae (N=12) Mesolawae (N=9) Mesolarvae (N=11) Metalarvae (N=9) Juveniles (N=8) i-±SD Range it- SD Range .T ± SD Range i±SD Range Y±- SD Range

SL, mm: 10 1 8 11 12 1 11 14 15 1 13 17 19 2 16 22 28 6 21 38 TL, mm: 10 1 8 12 13 1 11 15 16 1 15 19 22 3 18 27 34 7 25 45

Lengths %SL: AS to AE 2 0 1 3 3 1 2 4 5 1 4 6 7 1 6 8 8 1 7 9 PE 9 1 8 10 9 1 8 11 12 1 10 13 13 1 12 14 14 1 13 15 OP1 17 1 16 18 19 1 17 21 23 2 20 26 25 1 23 26 25 1 24 26 0P2 54 1 52 56 56 2 53 58 57 2 55 60 PY 73 5a 62 80 51 lc 50 52 OPAF 32 14 25 73 28 2 26 31 35 4 30 44 50 12 35 68 ODF 40 3 36 46 41 2 38 43 44 2` 41 47 49 49 49 OD 50 1 49 52 51 1 50 53 50 1 48 52 ID 62 lb 61 64 63 1 62 65 63 1 60 64 PV 78 2 75 81 77 1 75 78 79 1 77 80 77 1 75 78 75 1 74 78 OA 79 ld 77 79 77 1 76 78 76 1 74 78 IA 83 83 83 84 1 82 85 84 1 83 85 AFC 111 1 109 114 113 2 110 115 115 1 114 117 PC 104 1 101 106 107 1 105 109 113 2 110 118 118 2 115 120 121 1 119 123 47 17 0 67 3 6 0 14 P1 9 3 2 11 11 1 10 13 12 1 11 14 14 1 12 16 18 1 15 19 P2 4 2 1 8 8 1 6 11 12 1 10 13 13 le 11 15 17 1 15 19 20 1 18 21 A 8 lc 7 8 10 2 8 13 14 1 12 15

Depths %SL: at BPE 11 1 9 12 12 1 11 13 15 1 14 16 16 0 15 16 16 1 15 17 OP1 11 1 10 12 14 1 12 15 17 1 15 18 18 1 16 20 20 1 17 21 OD 12 lb 10 14 11 lb 10 12 13 lg 12 16 17 1 15 19 20 1 18 21 BPV 6 1 3 7 7 0 6 7 8 1 7 9 10 1 912 13 1 11 14 AMPM 3 1 2 4 4 0 4 5 6 1 5 6 7 1 6 8 9 0 8 9 Max. Yolk 5 4 0 13 0 1 0 1

Widths %SL: at BPE 10 1 8 11 11 1 10 13 14 1 13 16 15 1 14 16 16 1 15 17 OP1 7 2 6 12 9 1b 8 10 12 1 11 13 14 1 13 16 17 1 14 18 OD 8 2b 6 11 6 l 5 7 8 lg 7 10 12 1 10 14 15 1 13 17 BPV 4 0 3 4 4 0 4 4 5 1 4 5 7 1 6 9 9 1 810 AMPM 2 0 2 3 2 0 2 3 3 0 3 4 4 1 3 4 4 0 4 5 Max. Yolk 6 5 0 14 0 1 0 2

Myomeres: to PY 33 3a 26 35 23 lc 22 23 OPAF 10 7 5 29 7 1 6 9 9 2 7 13 18 7 9 28 0P2 21 1 19 22 21 1 20 22 22 Od 21 22 ODF 14 1 12 16 14 1 13 16 15 le 13 17 15 15 15 OD 19 1 17 19 18 1 16 19 18 ld 17 18 PV 36 1 35 37 36 1 35 37 36 1 34 37 35 1 32 36 34 ld 34 35 Total 45 1 44 46 46 1 44 47 45 1 43 46 45 1 43 45 45 ld 44 45

133 Fig. 70. Catostomus platyrhynchus protolarva, recently hatched, 8.1 mm SL, 8.2 mm TL (from Snyder 1983a). Cultured in 1981 with stock from Willow Creek, northwest of Steamboat Springs, Colorado.

•.0.110 JR40 • *FIR AL 41K, )11-

11.4111,,

.16 .•

Fig. 71. Catostomus platyrhynchus protolarva, 9.5 mm SL, 9.8 mm TL (from Snyder 1983a). Cultured in 1981 with stock from Willow Creek, northwest of Steamboat Springs, Colorado.

134 • ..••• • 4'4:4; • ••• 4•1•**4 • • • " - „ IF „ • •• • • ** • AV .8 • • 6 a* W *.•• • A

Fig. 72. Catostomus platyrhynchus flexion mesolarva, recently transformed, 12.1 mm SL, 12.8 mm TL (from Snyder 1983a). Cultured in 1981 with stock from Willow Creek, northwest of Steamboat Springs, Colorado.

Fig. 73. Catostomus platyrhynchus postflexion mesolarva, 13.7 mm SL, 15.6 mm TL. Collected in 1981 from Willow Creek, northwest of Steamboat Springs, Colorado.

135 Fig. 74. Catostomus platyrhynchus metalarva, recently transformed, 16.3 mm SL, 19.6 mm TL. Collected in 1981 from Willow Creek, northwest of Steamboat Springs, Colorado.

Fig. 75. Catostomus platyrhynchus metalarva, 19.6 mm SL, 22.5 mm TL. Collected in 1981 from Willow Creek, northwest of Steamboat Springs, Colorado.

136 Fig. 76. Catostomus platyrhynchus juvenile, recently transformed, 20.6 mm SL, 25.2 mm TL. Collected in 1985 from Spanish Fork River, Utah Lake, Utah.

Fig. 77. Catostomus platyrhynchus juvenile, 31.5 mm SL, 38.0 mm TL. Collected in 1983 from Provo River, Utah Lake, Utah.

137 Fig. 78. Selected skeletal features of Catostomus Fig. 79. Selected skeletal features of Catostomus platyrhynchus, juvenile, 21.2 mm SL, 24.0 mm TL. platyrhynchus, juvenile, 45 mm SL, 53 mm TL. Top Top — postcleithrum. Middle — anterior-dorsal maxil- — postcleithrum. Middle — anterior-dorsal maxillary lary projections. Bottom -- mandible position. projections. Bottom — mandible position.

138 Fig. 81. Frontoparietal fontanelle of Catostomus platyrhynchus. Top -- juvenile, 21.2 mm SL, 24.0 mm TL. Bottom juvenile, 45.0 mm SL, 53.0 mm TL.

Table 32. Dimensions of frontoparietal fontanelle for Catostomus platyrhyncluts larvae >16 mm SL, early (YOY) juveniles, and yearling.

Max. Max. Width Specimens width length as % of mm SL n (mm) (mm) length

17-19 0 20-21 2 0.6-0.8 2.2-2.2 27-36 1 0.7 2.2 32 Fig. 80. Interneurals of Catostomus platyrhynchus. 22-25 Top -- postflexion mesolarva, 14.8 mm SL, 17.0 mm 26-34 1 0.5 2.1 24 15-20 TL. Middle -- juvenile, 21.2 mm SL, 24.0 mm TL. 35-46 2 0.4-0.5 2.5-2.7 Bottom -- juvenile, 45.0 mm SL, 53.0 mm TL. 76-81 1 0 0 closed

139 Species Account -- Xyrauchen texanus

Fig. 82. Xyrauchen texanus, adult (from Behnke and Benson 1983). Adult Diagnosis: Conspicuous predorsal keel. Caudal peduncle deep. Mouth inferior, moderate in size. Lips moderately to weakly papillose, without notches at corners. Lower lip with median cleft that completely separates the two lobes. Fontanelle well developed. Peritoneum black. TL usually 40-60 cm, up to 90 cm. (Also, Table 33.) Reproduction: Non-guarding, open-substrate lithophil; possible redd creation. May and early June at 6-19°C in the Upper Colorado River Basin; Nov. to May, mostly Jan. to Mar. at 10-21°C in lower basin; usually with rising water levels. Spawn over gravel-cobble bars or riffles in rivers at <1 m/s, or near tributaries, in backwaters or along shore and coves of reservoirs over silt, sand, gravel, and rocks; under <6 m, usually <1 m, of water. Water-hardened eggs 25-2.8 mm diameter, demersal, and initially adhesive. Hatching unsuccessful or limited at 10°C, best around 20°C. Fig. 83. Regional distribution of Xyrauchen texanus. Young: At 18-20°C, hatch in 6-7, swim up in 12-13, and swim down in 27 days; at 15°C, 11, 17-21, and 38 days respectively. Remain in substrate until ready to migrate. Attracted by light at night. Larvae about 25 mm TL travel in large schools in warm shallows along shore. Table 33. Selected juvenile and adult meristics for Xyrauchen texanus. P = principal rays; R = rudimentary rays; D = dorsal; V = ventral. Scales are lateral series or line when complete. Four added to vertebral count for Weberian complex. Gill rakers for exterior row of first arch, specimens >100 mm SL. Mean or modal values underlined if known and noteworthy; rare or questionable extremes in parentheses.

Character Original Literature Character Original Literature Dorsal Fin Rays - P: (12)13-14-15-16 (12)13-14-15-16 Dorsal Fin Rays - R: 3-4(5) Anal Fin Rays - P: (6)7 7 Anal Fin Rays - R: (1)2-3 Caudal Fin Rays - P: 18 18 Caudal Fin Rays - RD: 10-T1-12-13 Pectoral Fin Rays: 15-16-17-18 16 Caudal Fin Rays - RV: 7-8-9-10 Pelvic Fin Rays: (9)10-11 10 Lateral Scales: 68-76-78-87(-95) Vertebrae: 45-46-47 Gill Rakers: 44-50 Table 34. Size at apparent onset of selected developmental events for Xyrauchen texanus, as observed under low power magnification. P = principal rays; R = rudimentary rays. Scales are lateral series. Rare or questionable extremes in parentheses.

Event or Onset or Formation Fin Rays First Formed Last Formed Structure mm SL mm TL or Scales mm SL mm TL mm SL mm TL Hatched: 7-9 7-10 Dorsal - P: 14 15 15(-17) 17(-20) Eyes Pigmented: (7)8(9) or " (7)8-9 or * Anal - P: 15 17 15-17 18-20 Yolk Assimilated: (9)10-11 (10)11-12 Caudal - P: (10)11(12) 11-12 (11)12-13 (13)14 Finfold Absorbed: (21)22-23(24) 27-30 Caudal - R 14 15-16 19-20(-24) 23-24(-30) Pectoral Fin Buds: 7 or * 7 or * Pectoral: 15 17 16-18 20-22 Pelvic Fin Buds: 14 15 Pelvic: 15-17 18-20 16-17 20-21 * before hatching Scales: 24-28 30-35 33-36(37) 42-45

References: Abbott 1860, Baxter and Simon 1970, Beckman 1952, Behnke et al. 1982, Bozek et al. 1984, Douglas 1952, Ellis 1914, Hubbs and Miller 1953, Jordan and Evermann 1896, La Rivers 1962, Lee et al. 1980, McAda 1977, Miller et al. 1982, Minckley 1973, Moyle 1976, Sigler and Miller 1963, Toney 1974, Tyus et al. 1982 and 1987, Wick et al. 1982, Woodling 1985. 140 Table 35. Size at developmental interval (left) and gut phase (right) transitions for Xyrauchen texanus. See Fig. 5 for phases of gut folding. Rare or questionable extremes in parentheses.

Transition to mm SL mm TL Transition to mm SL mm TL

0 Flexion Mesolarva: 11(12) 11-12 2 - 90 bend: (14)15(47) (16)17(-20) Postflexion Mesolarva: 12-13 (13)14 3 - Full loop: 17 20 Metalarva: 15-17 18-20 4 - Partial crossover 18-25(26) 22-30(-32) Juvenile: (21)22-23(24) 27-30 5 - Full cross over: (22-)26-28(-31) (27-)32-35(-38)

Table 36. Summary of morphometrics and myomere counts by developmental phase for Xyrauchen texanus. See Fig. 4 for abbreviations and methods of measurement and counting. Protolarvae with unpigmented eyes excluded.

Flexion Postflexion Protolarvae (N=25) Mesolarvae (N=13) Mesolarvae (N=25) Metalarvae (N=30) Juveniles (N=33) i±SD Range et ±SD- Range ± SD Range ±SD Range . ±SD- Range

SL, mm: 10 1 8 11 12 1 11 13 14 1 12 17 19 2 15 24 28 4 22 37 TL, mm: 10 1 9 12 12 1 11 14 16 2 13 20 23 3 18 30 36 6 27 47

Lengths %SL: AS to AE 2 0 1 3 2 1 2 3 5 1 3 7 7 1 4 9 8 1 6 9 PE 8 0 7 8 9 1 7 10 11 2 9 14 14 1 12 17 15 1 13 16 OP1 16 1 14 17 18 1 16 20 22 2 20 27 27 1 25 30 28 2 25 31 0P2 52 1° 50 54 56 b 2 51 58 57 2 54 60 PY 76 4 66 82 75 75 75 OPAF 30 12 22 66 27 2 24 30 31 3 27 36 42 9 34 69 ODF 34 2 32 39 37 3 33 44 42 3 d 36 45 45 2g 43 47 OD 49 1 47 51 49 1 47 51 49 1 46 52 ID 66 le 65 67 67 1 65 69 67 1 65 70 PV 79 2 76 81 79 1 78 81 81 1f 78 84 77 2 75 81 77 1 75 80 OA 81 1 79 82 77 1 76 79 78 1 75 80 IA 86 Of 85 86 84 1 83 86 84 1 82 86 AFC 110 2 107 114 114 1 111 117 115 1 113 118 PC 105 1 103 106 106 1 104 108 113 4 108 119 123 2 120 128 125 1 123 128 44 23 068 414 0 50 P1 7 3 3 11 10 1 9 11 11 1 9 13 15 1 12 18 17 1 15 19 P2 3 3 0 7 12 2 8 14 15 1 12 16 19 le 18 21 24 2 21 29 27 1 23 29 A 7 lg 5 9 12 l h 9 15 15 1 12 16

Depths %SL: at BPE 9 1 8 10 11 1 9 13 13 2 11 16 16 1 15 18 18 1 16 20 OP1 11 1 9 12 13 1 10 14 16 2 13 20 20 1 18 23 22 1 20 23 OD 10 2 7 13 9 1 6 11 14 3 9 20 19 2 16 23 23 2 18 27 BPV 5 1 4 6 6 0 5 6 7 1 5 9 11 1 814 13 1 11 14 AMPM 3 0 2 4 4 1 3 5 6 1 4 7 8 1 7 9 8 0 7 9 Max. Yolk 5 3 0 9 0 1 0 2

Widths %SL: at BPE 9 1 7 11 11 1 10 12 12 1 11 14 15 1 14 17 16 1 15 18 OP1 6 1 5 8 8 1 6 9 10 2 8 14 15 2 12 17 18 1 15 20 OD 6 2 4 9 5 0 5 6 8 2 5 11 11 2 815 16 2 12 20 BPV 3 0 2 4 3 0 3 4 5 1 3 6 6 1 4 9 8 1 6 9 AMPM 2 0 1 3 2 0 2 2 3 0 2 4 3 0 2 4 4 0 3 4 Max. Yolk 5 3 0 9 0 1 0 5

Myomeres: to PY 37 r 30 38 37 b 37 37 OPAF 10 6 531 7 0 6 8 7 1 6 9 10 5' 630 0P2 20 1` 19 22 20 1' 19 22 ODF 12 1 10 16 13 1 12 16 14 1 12 17 14 1g 12 15 OD 18 ld 16 20 16 1' 15 18 PV 39 1 37 41 38 1 37 39 39 1 38 40 37 1' 36 39 Total 48 1 46 49 47 1 46 49 47 1 46 49 46 1' 44 48 aN = 20; hN = 1; eN = 18; dN = 17; 'NI = 7; fisi = 5; gN = 6; hN = 29; 'N = 27

141 „

Fig. 84. Xyrauchen texanus protolarva, recently hatched, 9.2 mm SL, 9.4 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

,401410, -

Fig. 85. Xyrauchen texanus protolarva, 10.5 mm SL, 10.9 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

142

Fig. 86. Xyrauchen texanus flexion mesolarva, recently transformed, 12.5 mm SL, 12.9 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

• . 7 • ; 4, • • • . • .„ • • * • • • • • • • • • . . • • • * • • • • •

- • - 1:*•••■•••••••-••••• •

Fig. 87. Xyrauchen texanus postflexion mesolarva, 14.4 mm SL, 16.0 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

143 7 7 6_ 4 (

Fig. 88. Xyrauchen texanus metalarva, recently transformed, 16.2 mm SL, 19.4 mm IL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

• ' .

-.---- 111111°1 • 'f • , 1144

Fig. 89. Xyrauchen texanus metalarva, 18.8 mm SL, 22.8 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

144 b. 1 " • . ••••• . •

...

Fig. 90. Xyrauchen texanus juvenile, recently transformed, 21.6 mm SL, 27.0 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

Fig. 91. Xyrauchen texanus juvenile, 30.2 mm SL, 37.4 mm TL. Cultured in 1980 from stock in Colorado River gravel pits near Clifton, Colorado.

145 Fig. 92. Selected skeletal features of Xyrauchen Fig. 93. Selected skeletal features of Xyrauchen texanus, metalarva, 20.0 mm SL, 23.8 mm TL. texanus, juvenile, 40.5 mm SL, 51.0 mm TL. Top — postcleithrum. Middle — anterior-dorsal maxil- Top — postcleithrum. Middle -- anterior-dorsal maxillary projections. Bottom -- mandible position. lary projections. Bottom — mandible position.

146 Fig. 95. Frontoparietal fontanelle of Xyrauchen texanus. Top -- metalarva, 21.5 mm SL, 27.4 mm TL. Bottom -- juvenile, 26.1 mm SL, 32.0 mm TL.

Table 37. Dimensions of frontoparietal fontanelle for Xyrauchen texanus larvae >16 mm SL, early (YOY) juveniles, and yearling.

Max. Max. Width Specimens width length as % of mm SL n (mm) (mm) length

17-19 3 1.0-1.2 1.7-1.9 59-63 20-21 5 1.0-1.3 1.8-2.1 52-68 Fig. 94. Interneurals of Xyrauchen texanus. Top-- 22-25 2 1.0-1.3 1.9-2.1 53-62 postflexion mesolarva, 14.3 mm SL, 17.0 mm TL. 26-34 2 0.9-1.3 2.1-2.3 43-57 Middle -- metalarva, 20.0 mm SL, 23.8 mm TL. 35-46 3 1.1-1.7 2.3-3.4 48-50 Bottom -- juvenile, 40.5 mm SL, 51.0 mm TL. 76-81 1 2.3 5.1 45

147 LITERATURE CITED

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