BULLETIN of CARNEGIE MUSEUM of NATURAL HISTORY
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BULLETINISSN 0145-9058 OF CARNEGIE MUSEUM OF NATURAL HISTORY PHYLOGENETIC SYSTEMATICS OF CROTAPHYTID LIZARDS (REPTILIA: IGUANIA: CROTAPHYTIDAE) JIMMY A. McGUIRE NUMBER 32 PITTSBURGH, 1996 BULLETIN of CARNEGIE MUSEUM OF NATURAL HISTORY PHYLOGENETIC SYSTEMATICS OF CROTAPHYTID LIZARDS (REPTILIA: IGUANIA: CROTAPHYTIDAE) JIMMY A. McGUIRE Department of Biology, San Diego State University, San Diego, California 92182-0057 Current address: Department of Zoology and Texas Memorial Museum, The University of Texas at Austin, Austin, Texas 78712-1064. NUMBER 32 PITTSBURGH, 1996 BULLETIN OF CARNEGIE MUSEUM OF NATURAL HISTORY Number 32, pages 1-143, 52 figures Issued 25 June 1 996 James E. King, Director Editorial Staff: John L. Carter, Editor-, Bradley C. Livezey, Editor-, David R. Watters, Editor Mary Ann Schmidt, ELS, Assistant Editor Cover illustration: An adult male Crotaphytus dickersonae photographed approximately 2 km north of Bahia Kino Nuevo, Sonora, Mexico (see Fig. 3 IB). BULLETINS OF CARNEGIE MUSEUM OF NATURAL HISTORY are published at irregular intervals by Carnegie Museum of Natural History, 4400 Forbes Avenue, Pittsburgh, Pennsylvania 15213-4080, by the authority of the Board of Trustees of Carnegie Institute. © 1996 by Carnegie Institute, all rights reserved. ISSN 0145-9058 THE CARNEGIE MUSEUM OF NATURAL HISTORY Contents Abstract Introduction Historical Review Materials and Methods 6 Frequency Coding Allozyme Data Set 8 Ingroup Monophyly 8 Choice of Terminal Taxa 9 Outgroup Taxa 9 Morphology and Character Descriptions 11 Skull Roof 11 Palate 18 Braincase 20 Mandible 20 Miscellaneous Features of the Head Skeleton 24 Axial Skeleton 27 Pectoral Girdle 30 Pelvic Girdle 31 Limbs 32 Squamation 32 Pockets and Folds 36 Additional Morphological Characters 40 Coloration t 42 Behavioral Characters 52 Character List 54 Results 57 Discussion 63 Comparison with Previous Hypotheses 63 Character Evolution 65 Taxonomic Accounts 67 Crotaphytidae 67 Crotaphytus 68 C. antiquus 69 C. bidnetores 72 C. collaris 75 C. dickersonae 80 C. grismeri 83 C. insularis 84 C. nebrius 88 C. oligocenicus't 92 C. reticulatus 92 C. vestigium 94 Gambelia 97 G. copei 98 G. corona t 102 G. silus 102 G. wislizenii 106 Key to the Species of Crotaphytus and Gambelia Ill Acknowledgments 112 Literature Cited 113 iii Appendices 120 1. Specimens Examined 120 2. Data Matrix 126 3. Outgroup Data Matrix 128 4. Step Matrices for Manhattan Distance Frequency Approach 132 5. Character Transformations for Each Stem of the Single Most Parsimonious Tree 134 6. List of Character State Changes by Character 139 7. Scleral Ossicle Data 143 IV ABSTRACT A revision of the alpha taxonomy of Crotaphytidae revealed uous synapomorphies). The hypothesis of relationships estimated that there are at least 12 and probably 13 species. A data set here was used to address life history and morphological evolution including 88 characters drawn from osteology, squamation, soft within the group including the relationship between head mor- tissues, color pattern, life history, and behavior was collected. In phology and diet, the evolution of display-oriented morphology addition, an allozyme data set composed of ten phylogenetically in males, the evolution of bipedal locomotion, and a functional informative characters was obtained from the literature. Analysis consideration of gravid coloration. A taxonomic account is pro- of these data resulted in the following hypothesis of relationships: vided for Crotaphytidae, Crotaphytus, Gambelia, and each spe- - (( . cies. Gambelia silus (G. corona\ ( G copei + G. wislizenii))) + ( Cro Each species account includes a synonymy, an etymology, taphytus reticulatus (C. collaris (C. antiquus (C. nebrius (C. dick- a diagnosis for the species, a detailed description of scalation and ersonae (C. grismeri ( C. bicinctores (C. insularis + C. vestig- coloration, a section describing maximum adult size as well as ium))))))))). Although little character evidence in support of size dimorphism, a description of the species geographic distri- crotaphytid monophyly has been presented in the literature (Eth- bution with a dot distribution map, an account of the known eridge and de Queiroz, 1988; Frost and Etheridge, 1989), cro- fossil record, a summary of available natural history information, taphytid monophyly was found to be strongly supported with and a listing of references that provide illustrations of the species. five fixed, unambiguous synapomorphies. Strong support was Separate dichotomous keys are provided for males, females, and also discovered for monophyly of Crotaphytus (12 fixed, un- juveniles of Crotaphytus and Gambelia. ambiguous synapomorphies) and Gambelia (six fixed, unambig- 1 ? BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32 INTRODUCTION Lizards of the family Crotaphytidae (collared and 1975), phylogenetic relationships within Crotaphy- leopard lizards) are among the most familiar squa- tidae remain largely unresolved. Although the mates of western North America. This familiarity monophyly of the group has never been questioned, probably stems from their relatively large size (com- few derived characters have yet been offered to sup- pared to other North American lizards), often vi- port this contention (Etheridge and de Queiroz, 1988; brant coloration, predatory lifestyle, and pugnacious Frost and Etheridge, 1989). The same can be said habits. Crotaphytidae, one of nine iguanian families for the monophyly of the genera. The phylogenetic proposed by Frost and Etheridge (1989), is currently relationships of the group have been addressed using comprised of two genera, Crotaphytus (seven or eight cladistic methodology only once (Montanucci et ah, species) and Gambelia (three species), that range 1975), and that study predated important meth- from southern Idaho in the northwestern United odological advances in cladistics, such as outgroup States, southward into southern Baja California and analysis (Watrous and Wheeler, 1981; Maddison et northern Mexico, and eastward into the states of ah, 1984). Missouri, Arkansas, and Louisiana. They have been There are three primary goals of the present study. the subject of numerous studies of ecology, physi- The first goal is to revise the alpha taxonomy of ology, reproduction, hybridization, and historical Crotaphytidae in order to provide a better under- biogeography, and many of these studies have ad- standing of species diversity within the group as well dressed questions of a historical nature (e.g., Savage, as an appropriate selection of terminal taxa for phy- 1960; Montanucci, 1970; Ingram andTanner, 1971; logenetic analysis. The second goal is to provide an Axtell, 1972; Smith and Tanner, 1974; Montanucci estimate of the phylogenetic relationships of Cro- etal., 1975; Tanner and Banta, 1977; Tanner, 1978; taphytidae. The third goal is to use this phylogeny Sanborn and Loomis, 1979; Tollestrup, 1979, 1983; to investigate morphological and life history evo- Murphy, 1983; Welsh, 1988). However, despite sev- lution among crotaphytids and provide a taxonomy eral important systematic analyses of the group that is logically consistent with the evolutionary his- (Smith and Tanner, 1972, 1974; Montanucci et ah, tory of the group. HISTORICAL REVIEW The earliest accounts of crotaphytid lizards were tions, crotaphytid lizards have been thought to form closely associated with the joint military-scientific a natural group, despite the difficulty that more re- exploratory expeditions of the American frontier. In cent students have had in discovering synapomor- fact, it was only shortly after the epic Lewis and phies. Clark expedition of 1803-1806 that the first cro- In August of the same year, Baird and Girard taphytid species was described. As a member of a (18526) described two additional species of Crota- party headed by Major Stephen H. Long that was phytus'. C. dorsalis from the desert of Colorado, and exploring the Great Plains, Thomas Say collected C. gambelii, for which locality data was lacking, and later described Agama collaris (James, 1823). although it was thought to have been collected in Agama collaris was later placed as the sole member California. In December, Hallowed (1852) de- of the newly erected genus Crotaphytus by Holbrook scribed a fourth species, C. fasciatus (a junior syn- (1842) in his classic account of the North American onym of G. wislizenii), from the sand hills at the herpetofauna. lower end of Jornada del Muerte, New Mexico. Hal- A second crotaphytid species, Crotaphytus wisli- lowed's specimens were part of Samuel Wood- zenii, was obtained at Santa Fe (New Mexico) by house’s collections made during the early 1850s, Dr. Wislizenus, an army surgeon, who made the again emphasizing the important role that the early collection during the Mexican-American War of expeditions of the American West played in crota- by Baird phytid taxonomy. In 1854, Hallowed proposed the 1 846-1848. This species was first described description genus Dipsosaurus for C. dorsalis. and Girard ( 1 852 a), and a more detailed was given by the authors (1852c) shortly thereafter Dumeril (1856) transferred Crotaphytus collaris the Leiosaurus, a decision that was very in Stansbury (1852). From their first formal descrip- to genus 1996 McGUIRE — SYSTEMATICS OF CROTAPHYTID LIZARDS 3 likely influenced by the similarity in head mor- recognition of Crotaphytus baileyi at either the spe- phology and squamation in these genera. Further- cific or subspecific rank. Over the next 50 years, more, Dumeril (1856) suggested that C.