Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-1968 Systemic Studies of the Genus Gila (Cyprinidae) of the Colorado River Basin Paul Bernard Holden Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Biology Commons Recommended Citation Holden, Paul Bernard, "Systemic Studies of the Genus Gila (Cyprinidae) of the Colorado River Basin" (1968). All Graduate Theses and Dissertations. 2890. https://digitalcommons.usu.edu/etd/2890 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. SYSTEHATI C STUDIES OF THE GENUS GILA (CYPRINIDAE) OF THE COLORAD O RIVER BASIN by Paul Bernard Holden A thesis submitted in partial fulfillment of the requirements for the degree of HASTER OF SCIENCE in Fishery Biology UTAH STATE UNIVERSITY Log an, Utah 1968 ACKNOWLEDGMENTS The author is indebted to the late Dr. Donald R. Franklin whose efforts formed the groundwork for this study. Gratitude is expressed to Dr. Clair Stalnaker and Dr. Robert Behnke who guided the research and preparation of this manuscript. Thanks goes to several individuals who provided fish specimens; Rod Stone and John Livesay of the Utah State De partment of Fish and Game, Dr. W. Minckley of Arizona State University and Ernest Lachner of the U. S. National Museum. This project was financially supported by an NDEA Fellowship and the Utah Cooperative Fishery Unit . Paul B. Holden TABLE OF CONTENTS ACKNOWLEDGMENTS ii LIST OF TABLES iv LIST OF FIGURES v ABSTRACT vi INTRODUCTION DESCRIPTION AND DISTRIBUTION OF THE FO~ffi 4 PROCEDURES RESULTS . • 12 Results of the taximetric program by level 19 DISCUSSION 27 §_. robusta and Q. elegans 27 Q. elegans and Q. ~ 30 Q. robusta seminuda 35 Q. robusta intermedia 37 Q. robusta jordani 38 EVOLUTION AND PHYLOGENY 39 SUMMARY AND CONCLUSIONS 46 LITERATURE CITED 48 APPENDIXES 51 Ap pendix A. Annotated synonymy of t he s ubgenus Gila of t he Co l orado Ri ver basin 52 Appendix B. Characters and States as Used in the Taxi- me t ries Program 55 Appendix c. Tables 57 VITA 68 LIST OF TABLES Table Page 1. Summary of the intra- and interspecific morphol ogic relationships of robusta, elegans and cypha as determined in this study . 13 2 . Comparison of vertebrae numbers between members of the ~complex . 15 3 . Comparison of principal dorsal and anal fin ray counts between members of the Gila complex . 16 4. Comparison of gill raker number between members of the Gila complex 17 5. Comparison of predorsal lengths between members of the ~ complex 57 6. Comparison of anal origin to caudal base lengths between members of the Gila complex . • . • . 58 7. Comparison of head lengths between members of the Gila complex . 59 8 . Comparison of head depths between members of the Gila complex 60 9. Comparison of snout lengths between members of the ~complex 61 10. Comparisons of interorbital lengths between members of the Gila complex . 62 11. Comparison of pelvi c insertion to pectoral insert ion l engths between memb e rs of the Gila complex . 63 12. Comparison of snout to occiput lengths between members of the Gila complex . 64 13 . Comparison of jaw lengths between members of the Gila complex . 65 14 . Comparison of dorsal base lengths between members of the Gila complex 66 15 . Comparison of peduncle depths between members of the Gila complex 67 LIST OF FIGURES Figure Page 1. Q. ~ Q. elegans and Q. robusta from top to bottom . 5 2. Map of the Colorado River basin showing rivers and localities mentioned in the text . 8 3. Results of the taximetrics program for 309 Gila specimens 20 4. I ntergradation in morphology between Q. cvpha (top) and Q. elegans (bottom) 31 v ABSTRACT Systematic Studies of the Genus Gila (Cyprin~dge) of the Colorado River Basin by Paul Bernard Holden, Master of Science Utah State University, 1968 Major Professor: Dr. Clair Stalnaker Department: Wildlife Resourses Three hundred and nine specimens of Gila from the Colorado River basin were studied. A form of numerical taxonomy, taximetrics, was used to help classify the s pecimens. The data from these fish indicate that many of the present hypotheses concerning t heir taxonomy are not valid. The concept of ecosubspeci es or ecological subspecies does not fit the Colorado basin Gila. The roundtail and bonytail chubs, g. robusta Baird and Gir.ard and ~· elegans Baird and Girard respectively, currently treated as subspecies, are well separated morphologically, ecologicall y and reproductive ly and therefore are better considered two valid species . The relationship between g. ~M iller and Q· elegans is clouded by the presence of what appear to be intergrade forms . Future i nvestiga- tions are needed to piece t oge ther the puzzle surr ounding these two fis h. The subspecies name seminuda (Cope and Ya rrow) , present ly a ttributed to fish from throughout the Colorado basin, more correctly is allied to the~ of the Virgin River. Preliminary study indicates this popu- lation may be sufficiently different to warrent subs pecies recognition . No specimens of g. r obusta intermedia (Girard) were examined but the literature suggests this form may also be a valid species. (74 pages) INTRODUCTION The cyprinid genus Gila is presently divided into three subgenera; Gila , Siphateles and Snyderichthyes (Uyeno, 1960) . Richardsonius is included as another subgenus by some authors (Eddy, 1957) . This study is concerned with the systematics of the subgenus Gila of the Colorado River basin with emphasis on the upper basin forms presently recognized as f.~· r obusta (Baird and Girard), f. robusta elegans (Baird and Girard) and f · ~Miller. Baird and Girard (1853), working on fish collected in the Zuni River, Ne~' Nexico 1 described the genus Gila and three species,~· robusta, f. elegans and f. gracilis (Baird and Girard also published the descrip­ tions in the 1853 Proceedings of the Academy of Natural Sciences of Philadelphia, published in 1854). Cope and Yarrow (1875) named several Gila from collections of the Wheeler Survey in southwestern United States; included was f· seminuda from the Virgin River, Utah. By 1896, 13 species and five genera had been used for the Colorado River basin Gila . The revision by Jordan and Evermann (1896) reduced these to two genera (Gila and Leuciscus) and f ive species. Listed in Gila were three species, robusta, e legans and seminuda, with six synonyms. Leuciscus contained two species, intermedius (Girard) and niger (Cope) with two synonyms. Ellis (1914), with little critical examination , suggested that robusta and elegans might be considered one polymorphic species with a subspecies seminuda . Also, he listed Q. pandora (Cope) and f. egregia (Girard) as synonyms of r obus ta in error. Q· pandora refers t o the Gila of the upper Rio Grande basin, Q. egregia refers to the genus Richardsonius. Jordan, Evermann and Clark (1930) retained robusta, elegans and seminuda as f ul l species, and the two species of Leuciscus listed by Jordan and Evermann (1896) were both included under Tigoma gibbosa Girard. Miller (1946) described a new species, g. ~. from the Grand Canyon of Ari­ zona and suggested that robusta, elegans, seminuda and intermedia (Tigoma gibbosa) were only subspecies of a single species, robusta . Tanner (1950) named a new species, g. jordani, from the White River of Nevada. La Rivers (1962) considers this form a subspecies of g. robusta. The American Fisheries Society (1960) mentioned only g . robusta and g. ~ as full species. Uyeno (1960) established some of the relation­ ships between fishes allied to the genus Gila in an osteological study. His work primarily considered the taxonomy of this group above the species level. Appendix A is an annotated synonymy of the subgenus Gila of the Colorado basin. The present classification of ~ and elegans as subspecies does not fit the idea of subspecies being geographical units of species, for these forms are sympatric. It suggests rather that these forms are ecosubspeci es or ecological subspecies (Hubbs, 1943) which show rapid paralle l evolution in disjunct yet similar habitats, and therefore pre­ cludes the idea of a single evolutionary line for each form. Although these fish have been named several times by different authors, no thorough taxonomic study has been undertaken. Many of the hypotheses concerning the taxonom ic status of these forms have never been tested. The intent of this study was to contribute towards a better understanding of the populations referred to as the Gila complex . The objectives of the study were: 3 1. To determine the systematic relationships between the members of the Qi!! complex in the upper Colorado River basin. 2 . To determine the amount of intraspecific variation exhibited by the several members of this complex. 4 DESCRIPTION AND DISTRIBUTION OF THE FORMS The large amount of taxonomic confusion in these forms can be attributed to: instability of a few morphologic characters, notably squamation ; and an apparent cline in morphology believed to be adapted for varying current conditions which is the basis for the present ecosubspecies concept. At one end of the apparent c line is the small , chubby, generalized int ermedia of the Gila River basin (Arizona), thought of as a small stream form; robusta is hypothesized to be a slow to moderately swift current form of medium sized rivers; elegans is the intermediate form with characters adapted for life in large swift rivers; the morphology of ~ is hypothesized to be highly adapted for life at or near the bottom of torrential, turbid channels (Miller, 1946).