Late-Stage Larvae of the Family Microdesmidae (Teleostei, Gobioidei) from Belize, with Notes on Systematics and Biogeography in the Western Atlantic

BULLETIN OF MARINE SCIENCE, 67(3): 997–1012, 2000

LATE-STAGE LARVAE OF THE FAMILY MICRODESMIDAE (TELEOSTEI, GOBIOIDEI) FROM BELIZE, WITH NOTES ON SYSTEMATICS AND BIOGEOGRAPHY IN THE WESTERN ATLANTIC

David G. Smith and Christine E. Thacker

ABSTRACT Late-stage larvae of five species of wormfishes, family Microdesmidae, are described from Belize in the western Caribbean. They are distinguished by fin-ray and vertebral counts and chromatophore patterns. Cerdale floridana is widely distributed in the Carib- bean, southern Florida, and Bermuda. Microdesmus bahianus, originally known from southern Brazil and Martinique, was found to extend north and west as far as Panama and Belize. Meristic characters in M. bahianus vary geographically, with the population from Belize the most distinct. Microdesmus carri occurs only in the western Caribbean and the Gulf of Mexico. Microdesmus longipinnis occurs throughout the tropical and subtropical western Atlantic and shows a more complex pattern of variation; three more-or-less distinct populations were found. Finally, two specimens were collected at Belize that cannot be identified with a known species, although they show some resemblances to Microdesmus lanceolatus. Three of the species were reared through transformation to juveniles. Microdesmid adults are cryptic in habits and difficult to collect. Larvae, on the other hand, are easily collected in plankton nets. Larvae are thus more readily available and provide much valuable information on systematics and biogeography that would not be available from study of adults alone.

Microdesmids are small, elongate, gobioid fishes commonly known as wormfishes. They are benthic and often burrowing in habit and are found worldwide in tropical oceans and estuaries, favoring tidepools, reefs, and rocky, muddy or sandy habitats. We recog- nize five genera in the family: Cerdale, Clarkichthys, Microdesmus, Gunnellichthys and Paragunnellichthys. Two of these, Cerdale and Microdesmus, occur in the western Atlan- tic. Hoese (1984: 589) united these five genera with Ptereleotris and its allies in an expanded family Microdesmidae with two subfamilies, Microdesminae and Ptereleotrinae. Hoese’s classification has since been accepted more or less uncritically, even though Hoese himself seemed less than certain, stating that “two subfamilies are recognized here, but further studies may show both to be distinct families.” In an apparently little-noticed paper, Harrison (1989: 345) observed that one of Hoese’s most important characters, a “uniquely specialized...very long posterior pelvic process” in fact does not occur in the microdesmine genera Cerdale and Microdesmus. Harrison noted further distinctions between the two supposed subfamilies in the form of the maxilla and the palatopterygoquadrate complex. Studies by one of us (C.E.T.) fail to confirm the other characters reported by Hoese to be shared by the two groups, and we do not consider the ptereleotrines to be microdesmids. Seven species of Microdesmidae are known from the western Atlantic. Cerdale floridana Longley, 1934 occurs throughout the Caribbean, Florida, Bahamas, and Bermuda; C. fasciata Dawson, 1974 is known only from Brazil. Microdesmus bahianus Dawson, 1973 was described from Brazil and Martinique; we report it here from the western Caribbean. Microdesmus carri Gilbert, 1966 is known from the western Gulf of Mexico and the western Caribbean. Microdesmus lanceolatus Dawson, 1962 is currently known only from

997 998 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

the northern Gulf of Mexico, but evidence from larvae suggests a wider distribution. Microdesmus longipinnis is found throughout the western Atlantic and in the eastern tropical Atlantic. Microdesmus luscus Dawson 1977 occurs in the Caribbean. Microdesmids are uncommon in collections, with many species represented by only one or a few specimens. This is largely due to their ecology. After settling from the plankton, microdesmids live in burrows and substrate interstices, and are sampled effectively only with rotenone. Most species are found in depths of less than 3 m, in tidepools, estuaries, and sand or mud bottoms of mangrove swamps. One species, M. lanceolatus, ap- pears to inhabit somewhat deeper, offshore waters. Generally only one or a few specimens are taken in any collection, and sustained high doses of rotenone are required to cause them to emerge. Larvae, on the other hand, drift freely in open water and are commonly collected in plankton nets. They are thus much more accessible than adults and can provide much valuable information that would be unavailable through study of adults alone. A comprehensive revision of the Microdesmidae is beyond the scope of the present study, and we consider the present paper to be no more than a step toward that goal. We concern ourselves only with the species we have collected at Carrie Bow Cay, Belize, although we have examined comparative material from elsewhere in the western Atlantic to establish the distribution and geographic variation of some of the species. This paper is not intended to be a complete life-history study of the species treated. Our collections include only late-stage larvae nearly ready to settle out of the plankton, and we have no information on the sequence of fin formation, caudal flexion and other developmental landmarks. Indeed, such is not the purpose of our study. Our purpose is to extract as much information as we can from the material we have collected, and we hope that we will stimulate further study of these secretive little fishes.

MATERIAL AND METHODS

Our field work was conducted at the Smithsonian Institution’s research station at Carrie Bow Cay, on the outer edge of the barrier reef off Belize, Central America (16°48'N, 88°05'W), during periods of 2–3 wks between June and October in each of the years between 1992 and 1997, except 1995. Larvae were collected by suspending a 0.5 × 1 m rectangular plankton net off the dock on the seaward side of the island, which is located about 100 m from the reef crest. The current flows more or less continuously from east to west across the reef flat. The water at the site is little more than 0.3 m deep, so the net samples the entire water column from surface to bottom. Sampling usually began just after sunset and continued until about midnight. Tows varied in duration depending on the rate of flow and the amount of plankton in the water. The gentle rate of flow minimizes damage to the larvae, and many are still alive when brought into the laboratory. Individual larvae were picked up on a piece of plastic screen and put into a solution of MS-222 to anaesthetize them so that they could be examined under a microscope and typed. Some of these larvae were placed in a 10% solution of formalin in sea water and left overnight to fix. The next day they were transferred to 75% ethanol containing a small amount of BHT (butylated hydroxytoluene), an alcohol-soluble antioxidant that retards fading of the red and yellow color patterns. Selected larvae were photographed to record these ephemeral color patterns. Larvae that were not fixed were transferred to small, nylon-mesh breeder cages set in a raceway with a flow-through sea water system, where they were fed on brine shrimp (Artemia) nauplii three times a day. Captured microdesmid larvae were large, generally between 15 and 30 mm SL, depending on species, and while in the holding pens began to lose their larval pigmentation and develop adult morphology. Larvae were captured through- SMITH AND THACKER: MICRODESMID LARVAE 999

out the 2–3 wk sampling period and reared for up to an additional 4 wks, yielding a total of 5–7 wks of rearing time. At the end of that period, transformed juveniles were anaesthetized and fixed in 10% formalin, then transferred to 75% ethanol. Some specimens of each species were cleared and stained using the method of Potthoff (1984). One of us (D.G.S.) collected larvae of M. longipinnis at Man O’ War Bay, Tobago, in April 1998. Comparative material was studied from collections at the Gulf Coast Research Laboratory, Ocean Springs, MS, and the Museum of Comparative Zool- ogy, Harvard University, Cambridge, Massachusetts. Considerable verbiage has been expended over the years in attempting to put names on the various developmental stages of fishes. Little agreement has been reached. For our purposes and for the family we are treating, we consider all pre-settlement stages to be larvae.

Abbreviations used in the descriptions are as follows: D= dorsal fin, A= anal fin, P1= pectoral fin, P2= pelvic fin, V= vertebrae. The formula for the dorsal fin, which is continuous in microdesmids, is given as spines, soft rays = total (for example, XIX, 26 = 45). Vertebrae are given as precaudal + caudal = total. Methods of counting and measuring follow Dawson (1974: 410). For the rare species, we have listed all the material we have obtained. For C. floridana and M. bahianus, whose larvae are common, we have listed only the specimens from which we took meristic data and those that were reared or photographed. Institutional acronyms follow Leviton, et al. (1985). The illustrations are intended to convey the general appearance, shape, and melanophore pattern of the larvae; the number of fin rays and myomeres depicted are not necessarily accurate.

GENERAL MORPHOLOGY

Late-stage microdesmid larvae are relatively large, reaching approximately 11–30 mm SL before settling out of the plankton. They are elongate, with the anus near midlength, and have a conspicuous, bubble-like gas bladder slightly anterior to that point. The gut is a simple tube without swellings or loops. The anal fin extends from just posterior to the anus to a point just anterior to the base of the caudal fin. The dorsal fin is continuous, with no demarcation between the spinous and soft-rayed portions, extending from a point dorsal to or dorsal and slightly posterior to the tip of the appressed pectoral fin to a point just anterior to the base of the caudal fin. The caudal fin is emarginate, unlike the rounded or lanceolate tail seen in adults. In Microdesmus adults, the dorsal, caudal and anal fins are joined by folds of tissue, but this condition is not present in the larvae. The mouth is oblique, and the lower jaw strongly projects. A row of melanophores lies along the base of the anal fin and a much shorter row along the posterior end of the dorsal-fin base. Mel- anophores are present to a variable extent along the midventral line from the isthmus to the level of the gas bladder. We have observed three patterns in the distribution of these anteroventral melanophores. In C. floridana they are limited to a short, v-shaped patch below the base of the pectoral fin (Fig. 1A). In M. bahianus the v-shaped patch is followed posteriorly by a single median series of somewhat enlarged melanophores (Fig. 1B). In the other Microdesmus species, the v-shaped patch continues posteriorly as a double row of small melanophores (Fig. 1C). A short midlateral streak is present on the caudal peduncle of all except C. floridana. Red and yellow chromatophores occur vari- ably on the caudal peduncle and the proximal caudal-fin rays, along the base of the anal fin and the posterior base of the dorsal fin, and internally over the gut. 1000 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

Figure 1. Ventral pigment in microdesmid larvae. A, Cerdale floridana. B, Microdesmus bahianus. C, Other species of Microdesmus.

KEY TO LATE-STAGE MICRODESMID LARVAE FROM BELIZE

1a. No midlateral streak of melanophores on caudal peduncle ...... Cerdale floridana 1b. A midlateral streak of melanophores on caudal peduncle ...... 2 2a. Dorsal fin begins posterior to tip of appressed pectoral fin; ventral pigment in a single median row of somewhat enlarged melanophores (Fig. 1B) ...... Microdesmus bahianus 2b. Dorsal fin begins dorsal or anterior to tip of appressed pectoral fin; ventral pigment in form of two parallel rows of small melanophores, converging anteriorly below base of pectoral fin (Fig.1C) ...... 3 3a. Anal-fin rays 59–61 ...... Microdesmus sp. 3b. Anal-fin rays 56 or fewer ...... 4 4a. Dorsal-fin spines 26; midlateral pigment streak on caudal peduncle consisting of only one or two melanophores; caudal peduncle in fresh specimens red ...... Microdesmus carri 4b. Dorsal-fin spines 19–21; midlateral pigment streak on caudal peduncle consisting of more than two melanophores; caudal peduncle in fresh specimens yellow ...... Microdesmus longipinnis

Cerdale floridana Longley, 1934 (Fig. 1A, 2, 4A)

Description.—Body relatively short; dorsal fin beginning above posterior half of appressed pectoral fin. Size at settlement ca. 20 mm SL. Meristic characters (from 13 cleared and stained specimens): D.XIII, 31–33; A. 29–31; P1 14; V. 20+24–25 = 44–45. Anteriormost spine-bearing dorsal pterygiophore usually reduced and without an associ- SMITH AND THACKER: MICRODESMID LARVAE 1001

wly transformed juvenile, reared, LACM 47470-2. LACM transformed reared, juvenile, wly

. Top, pretransformation, 19 mm SL, USNM 350589. Bottom, ne Top, .

Cerdale floridana Cerdale

Figure 2. Figure 1002 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

ated spine; first spine-bearing dorsal pterygiophore inserting into 3rd-4th neural interspace (Fig. 4A). Melanophores.—A short, v-shaped pattern midventrally beneath pelvic fins, apex pointed forward, melanophores not extending posterior to tip of appressed pectoral fin (Fig. 1A). A paired series of melanophores along base of anal fin, the posteriormost 1–2 median and more intense than others in series. A short series of melanophores middorsally immediately anterior to base of caudal fin. Dense covering of melanophores on dorsal surface of gas bladder. Chromatophores.—Internal erythrophores at posterior end of skull around base of vertebral column. Diffuse erythrophores ventrally from lower jaw to gas bladder. A prominent series of orange-red chromatophores internally along top of gut from throat to gas bladder. Erythrophores along base of anal fin and internally on dorsal surface of vertebral centra. A wedge-shaped patch of orange-red laterally on caudal peduncle. Some erythrophores on proximal caudal rays. A series of diffuse xanthophores along posterior part of dorsal-fin base. Some xanthophores on proximal caudal rays. Juveniles.—Ground color of reared juveniles tan, with melanophore freckling on dorsal and lateral aspects (Fig. 2, bottom). Gill opening restricted, i.e., excluding most of pectoral-fin base. Remarks.—Larvae of this species were identified by the correspondence of meristic characters and by rearing specimens through transformation. C. floridana is the most common microdesmid larva collected at Carrie Bow Cay and one of two species whose adults have been collected in Belize. The species is found in Bermuda, southern Florida, the Bahamas, and throughout the Caribbean. We have examined specimens from various parts of its range and find no significant geographic variation in meristic characters. Material, larvae and reared juveniles (35 spec., 17.6–27.2 mm SL, all collected at Carrie Bow Cay).—LACM 47470-2 (3). USNM 350586 (4). USNM 350587 (2). USNM 350588 (4). USNM 350589 (1). USNM 350590 (3). USNM 350591 (18). Many additional specimens have been collected. Material, adults (22 spec., 19.5–65.0 mm SL).—Florida: USNM 102050 (presumed holotype); USNM 116991 (2, paratypes); UMMZ 186213 (1). Bermuda: ANSP 147841 (1); ANSP 147842 (1). Bahamas: ANSP 80576 (1); ANSP 81371 (1); ANSP 82101 (4); ANSP 144956 (1). Haiti: ANSP 119021 (1); ANSP 119023 (1); ANSP 119024 (1). Virgin Islands: ANSP 144666 (1). Lesser Antilles: ANSP 105753 (1); ANSP 105769 (1); ANSP 119022 (1). Panama: ANSP 117426 (1); GCRL 4615 (1).

Microdesmus bahianus Dawson, 1973 (Figs. 1B,3,4B)

Description.—Body relatively short, dorsal fin beginning posterior to a vertical through tip of appressed pectoral fin. Size at settlement ca 15 mm SL. Meristic characters (from

19 cleared and stained specimens, 10–15 mm SL): D. IX–XI, 26–29; A. 24–27; P1 11; V. 21–22 + 25–26 = 46–47. Anteriormost 4–6 dorsal-fin pterygiophores without spines; first spine-bearing dorsal pterygiophore inserting into 8th–9th neural interspace. (Fig. 4B). Melanophores.—Two small melanophores at tip of lower jaw, one on each side of sym- physis, and one at angle of lower jaw. An internal melanophore on each side at posteroventral SMITH AND THACKER: MICRODESMID LARVAE 1003

wly transformed juvenile, reared, LACM 47470-1. LACM transformed reared, juvenile, wly

.Top, pretransformation, 16 mm SL, USNM 350596. Bottom, ne .Top,

Microdesmus bahianus Microdesmus

Figure 3. Figure 1004 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

corner of neurocranium. An expanded melanophore on midventral surface of neurocranium. A paired series of expanded internal melanophores dorsal to gut from pectoral-fin base to gas bladder. An unpaired, median row of melanophores along midventral line from gular area to gas bladder, the anteriormost present as elongate dashes, the remainder rounded and expanded; a short v-shaped patch superimposed on anterior end of midventral series ventral to pectoral fin (Fig. 1B). Dorsal surface of gas bladder covered with melanophores. A paired series of melanophores along base of anal fin, posteriormost one or two median, more intense than others in series. A short middorsal series of melanophores from posterior end of dorsal fin to base of caudal fin. A short midlateral streak on caudal peduncle. Melanophores on proximal part of middle and lower caudal rays. Chromatophores.—Erythrophores ventrally on lower jaw, gular area, and midventrally below gut. Internal erythrophores on head below neurocranium. A series of erythrophores internally along dorsal surface of gut and along base of anal fin. A series of internal erythrophores on dorsal surface of vertebral centra, extending entire length of vertebral column. A series of internal erythrophores on ventral surface of vertebral centra, extending from level of anus to base of caudal fin. Xanthophores near tip of lower jaw and on posterior surface of neurocranium. Some xanthophores mixed with melanophores on dorsal surface of gas bladder. Xanthophores around centra of posterior ca 10 vertebrae, the posteriormost expanded into a wedge-shaped patch on caudal peduncle and base of caudal fin. A series of xanthophores along base of dorsal fin from approximate level of gas bladder to base of caudal fin. Juveniles.—The reared juveniles (Fig. 3, bottom) have a tan ground color with a stripe of melanophores dorsally from the snout to the caudal peduncle. A lateral stripe begins at the lower jaw and continues below the eye and above the base of the pectoral fin to the caudal peduncle. A bar extends ventrad from the eye to the gular area. These markings are prominent in transformed larvae and small adults. In larger adults, particularly preserved ones, the coloration is often paler. Remarks.—Microdesmus bahianus is unique among western Atlantic microdesmids in the configuration of the anterior dorsal-fin pterygiophores and spines: the anteriormost 4–5 dorsal pterygiophores are without spines, and the first spine-bearing pterygiophore inserts into 10th–11th neural interspace. In all other species, only the first pterygiophore is spineless, and the first spine-bearing pterygiophore inserts into the 3rd–4th neural interspace. M. bahianus was described from the South Atlantic coast of Brazil (Salvador) and the Caribbean island of Martinique (Dawson, 1973). We have also seen specimens from Panama. There is some clinal variation in the meristics over the length of the range. Our larvae from Belize have slightly lower counts than those reported for adults collected farther south. This is most noticeable in the precaudal vertebrae, which number 21–22 (13 specimens, mean 21.15) in the Belize larvae, 26 in the holotype from Brazil, and 24– 25 (4 specimens, mean 24.25) from Panama. Slighter but still significant differences are found in anal rays (24–26, mean 25.27 in Belize; 26–28, mean 26.86 in Panama; 27 in Martinique; 26–28, mean 26.90 in Brazil), and dorsal spines (9–11, mean 10.25 in Belize; 10–12, mean 11.00 in Panama; 12 in Martinique; 12–13, mean 12.60 in Brazil). In dorsal spines and precaudal vertebrae, the Panama specimens are somewhat intermediate between the Belize and Brazil specimens, but in anal rays, the Panama specimens fall closer to the Brazilian ones. SMITH AND THACKER: MICRODESMID LARVAE 1005

Figure 4. Anterior skeletal elements. A, Cerdale floridana, with a single rayless pterygiophore, and first spine-bearing pterygiophore inserting into fourth neural interspace; this pattern also present on all other species except Microdesmus bahianus. B, Microdesmus bahianus, with four rayless pterygiophores, and first spine-bearing pterygiophore inserting into eighth neural interspace.

M. bahianus and C. floridana together comprise the great majority of microdesmid larvae collected at Carrie Bow Cay. In spite of the abundance of larvae, adults of M. bahianus have not been collected in Belize. Material, larvae and reared juveniles (28 spec., 12.0–18.5 mm SL).— LACM 47470- 1 (2). USNM 350592 (13). USNM 350593 (1). USNM 350594 (3). USNM 350595 (7). USNM 350596 (1). USNM 350593 (1). Numerous additional specimens were collected. Material, adults (29 spec., 17.1–64.8 mm SL).— Brazil: USNM 209216 (holotype); GCRL 10711 (1); GCRL 10715 (12); GCRL 11101 (2); USNM 209537 (2); USNM 274853 (1). Martinique: ANSP 103427 (1). Panama: GCRL 10712 (5); GCRL 10716 (3): GCRL 12043 (1).

Microdesmus carri Gilbert, 1966 (Figs. 1C,4A,5)

Description.—Body elongate, dorsal fin beginning over posterior part of appressed pectoral fin. Size at settlement ca 33–36 mm SL. Meristic characters (from one cleared and stained specimen): D. XXVI , 46 = 72, A. 38, P1 13, vertebrae 38 + 31 = 69. Anteriormost dorsal pterygiophore reduced, without an associated spine; first spine-bearing dorsal pterygiophore inserting into fourth neural interspace (Fig. 4A). 1006 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

, pretransformation, 27 mm SL, USNM 350902.

Microdesmus carri Microdesmus

Figure 5. Figure SMITH AND THACKER: MICRODESMID LARVAE 1007

Melanophores.—Horizontally elongate melanophores along midventral line from throat to a point approximately half a head length anterior to gas bladder, in a single row anterior to level of pectoral-fin base, diverging into a paired series posterior to that point (Fig. 1C). A paired series of melanophores along base of anal fin, followed by two or three median melanophores on midventral line just behind anal fin. A short middorsal series of melanophores between posterior end of dorsal fin and base of caudal fin. One or two midlateral melanophores on posterior end of caudal peduncle. Melanophores on proximal portion of middle caudal rays and distally on ventral caudal rays. Melanophores internally on dorsal surface of air bladder and posteroventrally on neurocranium. Chromatophores.—Erythrophores on upper jaw just behind tip of snout, near tip of lower jaw, behind angle of jaw, and dorsally over middle of neurocranium. A series of erythrophores midventrally from throat to about level of gas bladder. Erythrophores internally forming an unbroken series along dorsal surface of gut from anterior end of esophagus to level of gas bladder. A series of erythrophores internally on dorsal surface of vertebral centra, extending entire length of vertebral column. Erythrophores along base of anal fin. A broad reddish patch covering lateral surface of caudal peduncle. A series of xanthophores along posterior part of dorsal-fin base, forming a continuous yellow streak. A narrow yellow bar at proximal end of caudal-fin rays. Remarks.—We did not rear this species. The fin-ray and vertebral counts of our larva agree with those of M. carri: D. XXV–XXVI, 43–47; A. 33–39; V. 36–38 + 30–32 = 66– 69 (data from Gilbert, 1966 and from specimens examined by us). Gilbert’s type material consisted of both pre- and post-transformational individuals. His two largest specimens, 36.5 and 53.0 mm SL, were well pigmented, had a rounded caudal fin, and the dorsal and anal fins were adnate to the caudal fin. The remaining specimens, 28.0–33.5 mm SL, were unpigmented, had an emarginate caudal fin, and the dorsal and anal fins were sepa- rate from the caudal fin. This indicates that settlement and transformation occur at a SL of between approximately 33.5 and 36.5 mm. M. carri is known only from the western Caribbean and the southwestern Gulf of Mexico. There is little evidence of geographic variation in meristic counts, with the possible exception of anal-fin rays: 33–36, mean 35.63 in the type material from Costa Rica; 35–38, mean 36.50 in two Belize specimens; and 35–39, mean 37.00 in 14 specimens from Veracruz, Mexico. Material, larvae (9 spec., 24.0–33.0 mm SL).—Costa Rica: USNM 208573 (2 paratypes), USNM 209096 (2 paratypes, published as USNM 257754-F2 in Gilbert, 1966), ANSP 102210 (2). Belize: USNM 350900 (1, 24.0), USNM 350901 (1), USNM 350902 (1). Material, adults and juveniles (19 spec., 32.2–136.9 mm SL).—Veracruz, Mexico: GCRL 2412 (15), GCRL 4607 (1), GCRL 4608 (2). Belize: USNM 306030 (1).

Microdesmus longipinnis (Weymouth, 1910) (Figs. 1C,4A,6)

Description.—Body relatively elongate, dorsal fin beginning over posterior part of appressed pectoral fin. Size at settlement ca 23 mm SL. Meristic characters (from five cleared and stained specimens and three alcohol-preserved specimens): D. XIX–XXI,

48–56 = 67–75, A. 40–52, P1 14, vertebrae 29–32 + 33–39 = 62–71. Anteriormost dorsal 1008 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

wly transformed reared. juvenile, wly

. Top, pretransformation, 22.6 mm SL, USNM 350898. Bottom, ne Top, .

Microdesmus longipinnis Microdesmus

Figure 6. Figure SMITH AND THACKER: MICRODESMID LARVAE 1009

pterygiophore reduced, without an associated spine; first spine-bearing dorsal pterygiophore inserting into fourth neural interspace (Fig. 4A). Melanophores.—Horizontally elongate melanophores along midventral line from throat to gas bladder, in a single series anterior to level of pectoral-fin base, diverging into a double row posterior to that point (Fig. 1C). A paired series of melanophores along base of anal fin, the posteriormost one or two median and more intense than others. A short series of melanophores middorsally from posterior end of dorsal fin to base of caudal fin. Three to five midlateral melanophores on caudal peduncle forming a longitudinal streak. Small melanophores on proximal part of middle caudal rays. Chromatophores.—Red under gular area, diffuse yellow on snout. Erythrophores mixed with melanophores on ventral midline. Caudal peduncle broadly suffused with yellow, yellow extending posteriorly onto basal part of caudal rays and anteriorly along dorsal margin of body to a point approximately midway between gas bladder and base of caudal fin. Some red on ventral part of caudal peduncle just behind posteriormost ventral melanophore, angling anterodorsally to level of vertebral column. Some diffuse red around posteriormost vertebral centra medial to anterior midlateral melanophores. Juveniles.—Ground color tan, melanophores scattered over dorsal and lateral portions of body, with mottling extending onto face, and more intensely in a single stripe along dorsum and in a poorly defined thin stripe laterally extending from head to caudal peduncle. These stripes not the same as the thick, distinct dark stripes found in some other species, but rather areas of somewhat more intense concentrations of melanophores. Remarks.—Microdesmus longipinnis is the most widely distributed of the Atlantic microdesmid species, and its meristic characters vary. The complete range of counts assembled by us are: D. XIX-XXIII, 40–58 = 62–80; A. 36–52; V. 29–32 + 30–39 = 59–71. Within this broad range, we can distinguish three more or less distinct subgroups. The majority of specimens have 66–75 total dorsal elements (n = 196), 40–47 anal rays (n = 178), and 62–66 total vertebrae (n = 39). Dawson (1962) found three specimens from off the west coast of Florida with unusually low counts: 62–64 dorsal elements, 36–41 anal rays. We identified one adult (USNM 196615), also from the west coast of Florida, with similar counts: D. XXIII, 40 = 63; A. 40; V. 29 + 30 = 59. A third variant, characterized by unusually high counts, is represented by one larva (MCZ 124967, collected at 11°N, 78°W), with counts of D. XIX, 56 = 75, A. 52, V. 32 + 39 = 71, and one adult (GCRL 22109, from Veracruz, Mexico) with counts of D. XXII, 58 = 80, A. 52, V. 32 + 37 = 69. Material, larvae and reared juveniles (49 spec., 10.8–35 mm SL).—Gulf of Mexico: GCRL 13883 (34). Florida Atlantic: MCZ 124956 (1). Belize: USNM 350894 (4); USNM 350895 (1); USNM 350896 (1); USNM 350897 (1); USNM 350899 (1). Panama: MCZ 124967 (2). Tobago: USNM 350898 (2). Off Brazil: MCZ 124954 (1). West Africa: MCZ 124958 (1). Material, adults and juveniles (74 spec., 17.0-191 mm SL).— Gulf of Mexico: USNM 64157 (holotype); GCRL 286 (50); GCRL 2408 (11); GCRL 22109 (1); USNM 107251 (1); USNM 107753 (1); USNM 117614 (2); USNM 121989 (1); USNM 121990 (1); USNM 196615 (1); USNM 207751 (3). Puerto Rico: ANSP 144350 (1). 1010 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

sp., pretransformation, 30 mm SL, USNM 350904.

Microdesmus

Figure 7. Figure SMITH AND THACKER: MICRODESMID LARVAE 1011

Microdesmus sp. (Figs. 1C,4A,7)

Description.—Body elongate, dorsal fin beginning over posterior part of appressed pectoral fin. Size at settlement at least 30 mm SL. Meristic characters (from one cleared and stained specimen): D. XIV, 61–64 = 75–78; A. 59–61; V. 24 + 44 = 68. Melanophores.—Two rows of melanophores along bottom of gut, converging anteriorly near level of pectoral fin (Fig. 1C). Melanophores mid-ventrally along base of anal fin and mid-dorsally at posterior base of dorsal fin. A few melanophores laterally on caudal peduncle. Chromatophores.—Notes made at the time of capture indicate a yellow patch on caudal peduncle, with a horizontal extension onto proximal part of middle caudal rays. The specimen was not photographed, and we have no further information on chromatophores. Remarks.—No known species of microdesmid matches the fin-ray and vertebral count of this larva, but the relatively low number of dorsal spines combined with the high number of total dorsal elements is similar to the condition in M. lanceolatus Dawson, 1962. Only two adult specimens of M. lanceolatus are known: the holotype and one other specimen, both from the northern Gulf of Mexico. We have, however, assembled counts from 15 larval specimens with similar dorsal-spine/dorsal-ray configurations (i.e., low spine number, high total number): three from the Gulf of Mexico and 12 from off the Guianas. Specimens from the Gulf of Mexico have the following counts: D. XI-XIII, 51–56 = 62– 68; A. 52–55; V. 22 + 38–39 = 60–61. Specimens from the Guianas have the following counts: D. XII–XIII, 56–61 = 68–73; A. 48–56; V. 22–23 + 39–44 = 62–67. The counts of our Microdesmus sp. larvae lie outside the range of both of the other groups, even though they are geographically intermediate; the variation is thus not a simple cline. M. longipinnis specimens also fall into three groups based on fin-ray and vertebral counts, but the pattern is different, i.e., one wide-ranging form with two other forms embedded within it. With the lanceolatus group, the three forms are all geographically distinct. At this point, we can only suggest that Microdesmus sp. represents an undescribed species, possibly related to M. lanceolatus. This is the rarest of our larvae, represented by only two specimens, both collected on the same night, 14 June 1993. It is also the largest of our microdesmid larvae, reaching at least 30 mm SL before settlement. Material, larvae (2 specimens, 26–30 mm SL).— USNM 350903 (1); USNM 350904 (1).

ACKNOWLEDGMENTS

Our work at Carrie Bow Cay was supported by the Caribbean Coral Reef Ecosystems program at the National Museum of Natural History, K. Ruetzler, director. Assistance in the field was provided by C. C. Baldwin, M. R. Carpenter, K. C. Cole, and B. Pfeiffer. We thank G. D. Johnson for his support of our studies. The MCZ specimens were made available to us by K. Liem and K. Hartel. S. G. Poss and M. O’Connell provided access to the GCRL collections. J. Meganan (UMMZ) pre- pared the illustrations of the transformed juveniles of Cerdale floridana, Microdesmus bahianus, and M. longipinnis (Figs. 2, bottom; 3, bottom; and 6, bottom). The senior author thanks J. D. Hardy for making possible his trip to Tobago. This is Contribution No. 591 of the Caribbean Coral Reef Ecosystems Program. 1012 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 3, 2000

LITERATURE CITED

Dawson, C. E. 1962. A new gobioid fish, Microdesmus lanceolatus, from the Gulf of Mexico with notes on M. longipinnis (Weymouth). Copeia 1962(2): 330–336. ______. 1973. Microdesmus bahianus, a new western Atlantic wormfish (Pisces: Microdesmidae). Proc. Biol. Soc. Wash. 86(17): 203–210.

______. 1974. A review of the Microdesmidae (Pisces: Gobioidea) 1. Cerdale and Clarkichthys with descriptions of three new species. Copeia 1974(2): 409–448. Gilbert, C. R. 1966. Two new wormfishes (family Microdesmidae) from Costa Rica. Copeia 1966(2): 325–332. Harrison, I. J. 1989. Specialization of the gobioid palatopterygoquadrate complex and its relevance to gobioid systematics. J. Nat. Hist. 23: 325–353. Hoese, D. F. 1984. Gobioidei: relationships. Pages 588–59 in H. G. Moser, et al., eds. Ontogeny and systematics of fishes. Spec. Publ. no. 1, Amer. Soc. Ichthyol. Herpetol. 760 p. Leviton, A. E., R. H. Gibbs, Jr., E. Heal and C. E. Dawson. 1985. Standards in herpetology and ichthyology: Part I. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia 1985(3): 802–832. Potthoff, T. 1984. Clearing and staining techniques. Pages 35–37 in H. G. Moser, et al., eds. Ontog- eny and systematics of fishes. Spec. Publ. no. 1, Amer. Soc. Ichthyol. Herpetol. 760 p.

DATE SUBMITTED: December 28, 1999. DATE ACCEPTED: May 8, 2000.

ADDRESSES: (D.G.S.) Division of Fishes, MRC-159, National Museum of Natural History Washington, DC 20560-0159. (C.E.T.) Museum of Zoology, University of Michigan, Ann Arbor, MI 48109. Present Address: Section of Vertebrates, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, California 90007-4000.