McGUIRE-SYSTEMATICS OF CROTAPHYTID IlZARDS
BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32 variable with respect to the white component of the dorsum, this variation was coded as an unordered multistate character. The Gambelia condition often consists of broad, white or cream-colored, offsetting transverse bars with large, brown dorsal spots and is coded as state 0; the C. reticulatus and C. antiquus condition of a white reticulum, some or all of which enclose black pigmentation, is coded as state 1; the pattern composed of numerous small white spots (present in C. bicinctores, C. collaris, C. dickersonae, C. grismeri, and C. nebrius) is coded as state 2; the C. vestigittm condition of white, transverse dorsal bands on a background of white spots and dashes is coded as state 3, and the C. insularis condition of wavy, white dorsal dashes is coded as state 4. This character was left unpolarized. Sesual Dichrornatism (Character 69; Fig. 3 1 B, C).-Sexual dichromatism is widespread within the Iguania (Cooper and Greenberg, 1992) and, thus, it is not surprising that most crotaphytids also display strong sexual dichromatism. However, Gambelia and Crotaphytus reticulatus generally lack sexual di- chromatism in their permanent dorsal patterns (al- though G. silus and C. reticulatus do have male breeding coloration). There is obvious sexual di- chromatism in the gular pattern and femoral pore coloration and a small amount of sexual variation in the collar of C. reticulatus. However, the re- maining species of Crotaphytus have much more obvious sexual dichromatism throughout the year, with males differing from females in most aspects of dorsal coloration (e.g., much more vibrant blue, green, and/or yellow dorsal coloration in C. collaris), as well as in the gular pattern. Although sexualdi- chromatism is present in many iguanian taxa, data could not be obtained for many of the more obscure and poorly known species. Therefore, this character was left unpolarized. Paired Melanic Keels on Scales of Ventral Caudal Extremity (Character 70). -All Crotaphytus species except C. reticulatus (50 specimens examined) and C. insularis (23 specimens examined) are charac- terized by the presence, in at least some individuals, of darkly pigmented obtuse keels on the scales of the ventral surface of the tail tip (noted as present in C. nebrius and some C. collaris by Axtell and Montanucci, 1977). These take the appearance of paired dark spots that may extend along the ventral surface of the tail over the distal 2-30 mm. This feature is fixed in some species, polymorphic in oth- ers, and the percentage of individuals with the pig- mented keels may vary extensively between popu- lations of the same species. Crotaphyt~ts collaris is polymorphic with respect to this character and there is much geographic variation in the percentage of individuals with the paired pigmented scales. Individuals from regions of Mexico generally referred to the subspecies C. c. firsclcs and C. c. baileyi usually possess this character (2 1 of 33 specimens examined). It is less often present (six of 23) in specimens from midwestern and southern United States (generally referred to the subspecies C. c. collaris). It was absent in all specimens of C. collaris examined from Arizona, eastern Utah, and western Colorado (generally referred to the subspecies C. c. baileyi and C. c. auriceps, n = 38). Although the percentage of individuals with pigmented keels varies regionally, the observed frequency for C. collaris (29 of 94) was employed in the phylogenetic analysis. In Crotaphytus nebrius, this characteristic appears to be nearly fixed. The pigmented scales were observed in 48 of 49 specimens examined. The only specimen that lacked the scales (KU 12 1460) was from the Tucson <strong>Mountain</strong>s, an isolated range inhabited by what may be a distinct species. Unfortunately, this is one ofonly two preserved specimens available from the Tucson <strong>Mountain</strong>s (the other specimen, SDSNH 15208, had pigmented scales). The pigmented scales are much darker, and thus more obvious, in C. nebriics than in C. collaris. Crotaphytw bicinctores is another species in which this characteristic is polymorphic. It was present in 37 of 79 specimens examined. However, the percentage of individuals with the pigmented scales varied considerably between populations. Specimens from southern populations (Palo Verde <strong>Mountain</strong>s, California; Chocolate <strong>Mountain</strong>s, California; Kofa <strong>Mountain</strong>s, Arizona; Sentinel, Arizona) have the scales in high frequency (26 of 32), while specimens from more northern populations (Idaho; Inyo County, California; Washington County, Utah) usually lack them (present in three of 30 specimens examined). The pigmented scales appear to be fixed in Crotaphytus dickersonae (present in 44 of 44 specimens examined), C. grismeri (present in ten of ten specimens examined), C. vestigium (present in 43 of 43 specimens examined), and in C. antiquus (present in 17 of 17 specimens examined). The presence of paired melanic keels on the distal caudal extremity is considered to be the derived state as they appear to be unique to Crotaphytus. Black Oral Mucosa (Character 7 I).-In all crotaphytids except Crotaphyttcs bicinctores, C. gristneri, C. insularis, and C. ~~estigium, black pigments