McGUIRE-SY STEMATICS OF CROTAPHYTID LIZARDS pores extend beyond angle of knee, separated me- dially by 14 to 25 granular scales. Subdigital la- mellae on fourth toe 18 to 25. Coloration in Lqe. -The dorsal pattern of G. wis- lizenii is extremely variable, with several color morphs that are more or less confined to specific geographic regions. These pattern classes conform to the subspecies ~vislizenii, punctattrs, and macu- losus (Montanucci, 1978; although he recognized an additional unnamed pattern class as well) that are not recognized here. They differ most notably in the size of the dorsal spots (large in the tnaculosus pat- tern class, intermediate in tvislizenii. and small in punctatus), as well as in the character of the dorsal transverse bars. The dorsal spots are often scattered over the dorsum irregularly, extend well down onto the flanks, and continue onto the dorsal and lateral surfaces of the head. The dorsal base color for most individuals is white, cream, or gray, although some individuals apparently may approach the brown col- oration of northern G. copei (Montanucci, 1978). Gravid coloration in G. ivislizenii is similar to that of G. copei with orange or red spots often pres- ent on the head and/or neck, in two rows of spots on each flank, and on the ventral surface of the tail. The red or orange pigments occasionally may extend onto the thighs. Males lack any form of breeding coloration. A more detailed description of geographic vari- ation in the dorsal pattern of Gambelia tvislizenii is provided in Montanucci (1 978). Size. -This species exhibits strong sexual dimor- phism with females reaching larger adult size (max- imum observed SVL = 144 mm) than males (max- imum observed SVL = 1 19 mm; Tollestrup, 1979, 1982). Distribution (Fig. 52). - Gambelia Ivislizenii oc- curs in the western United States and northern Mex- ico, ranging from eastern Oregon and southern Ida- ho in the north, at least as far south as central Sonora in the west, and southern Coahuila or northern Za- catecas in the east. This species extends westward well beyond the limits of the lower Colorado Desert in southern California where it has been collected at Temecula, near Vail Lake, and at Arlington in Riverside County. However, a specimen purport- edly collected at Arcadia, Los Angeles County (FMNH 203919), seems suspect. The species ap- pears to be absent from the high elevation moun- tains of eastern Arizona and adjacent western New Mexico. Its distribution also appears to be limited in Texas, with a number of specimens known from the sandy northern portion of the Texas panhandle and from the Chihuahuan Desert habitats between Big Bend National Park and El Paso. It is unclear whether G. wislizenii is continuously distributed in the western portion of Texas between Reeves, Ward, and Crane counties and the southern portions of Brewster and Presidio counties. Specimens are rel- atively few from most of northern Mexico, but it appears that G. tvislizenii is completely excluded from the higher portions of the Sierra Madre Oc- cidental of eastern Sonora and western Chihuahua. Garnbelia ivislizenii and G. copei occur together in a narrow zone ofsyntopy in northern Baja California which is denoted in Figure 52 by an oblong oval marking (for a more extensive discussion of this zone of syntopy, see the G. copei account above). The two northern Oregon localities shown on Figure 52 are old records from The Dalles, Wasco County, and Hat Rock, Umatillo County. The symbol "?" shown on Figure 52 represents a record from Che- ney, Spokane County, Washington. The northern Oregon and Washington records should be consid- ered questionable until verified by additional field work. Fossil Record. -Numerous Pleistocene fossils have been referred to this species (Estes, 1983) in- cluding a pair ofmaxillae that may be more properly referred to Gatnbelia silus (see G. silus account for comments). Natzrral History. -There is extensive literature as- sociated with the natural history and ecology of Gambelia kvislizenii. The reader is referred to the following papers for a more detailed discussion of this topic: McCoy, 1967; Montanucci, 1967, 1970, 1978; Turner et al., 1969; Tanner and Krogh, 1974a, 1974b; Essghaier and Johnson, 1975; Parker and Pianka, 1976; Tollestrup, 1979, 1982, 1983; and Mitchell, 1984. This widespread species occurs in a number of habitat types, although it is found pri- marily on desert flats and lower foothills character- ized by sparse vegetation. Throughout much of its range in the Sonoran, Mojave, Great Basin, and Chihuahuan deserts it is found in flatlands in as- sociation with creosote bush (Larrea tridenrata) as well as other xerophilic plants. In the Pyramid Lake region of northwestern Nevada, it is found in as- sociation with filaree storksbill (Erodiunt cicutar- ium), mormon tea (Ephedra nevadensis), four-wing saltbush (Atriplex canescens), and Grayia spinosa (Snyder, 1972). Tollestrup (1 979, 1982, 1983) stud- ied G. ivislizenii near California City, California, where the dominant shrub was creosote bush (Lar-
108 BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32 40 30 150 Km - 120 110 100 Grand Junction ' *:k~lbuquerque 110 100 Fig. 52.-Geographic distribution of Gambelia ~~islizenii. The elongate ovoid marking in northern Baja California represents the narrow zone in which G. wislizenii and G. copei occur together. The "?" denotes a questionable locality record from Cheney, Spokane County, Washington. 40 30
Change language