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96 BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32<br />

individuals occurring between Bahia de San Luis<br />

Gonzaga and Bahia de Los Angeles is not known.<br />

The gular coloration in adult males is generally slate<br />

gray or gun-barrel blue, with a black central gular<br />

component. The peripheral gular pattern is the stan-<br />

dard reticulate form. Anterior collar markings are<br />

always present and posterior collar marks are only<br />

rarely lacking. The posterior markings are widely<br />

separated middorsally. The anterior collar markings<br />

are complete ventrally in adult males, with black<br />

pigments extending through the gular fold. A pair<br />

of black nuchal spots are not present middorsally<br />

between the anterior collar markings. Enlarged me-<br />

lanic axillary patches immediately posterior to the<br />

forelimb insertion are variably present. Large me-<br />

lanic inguinal patches are always present. The fem-<br />

oral pores are generally off-white to gray in color.<br />

Paired, melanic keels are always present on the ven-<br />

tral surface of the caudal extremity.<br />

Females are less vividly marked than males. The<br />

dorsal coloration is usually gray or greenish gray.<br />

The head and gular markings are less developed and<br />

male color pattern characteristics such as the white<br />

dorsal caudal stripe, ventrally complete anterior col-<br />

lar markings, and melanic inguinal patches, axillary<br />

patches, and central gular spot are lacking. Gravid<br />

females develop vivid orange or reddish lateral bars.<br />

The tail is not brightly colored in adult or subadult<br />

females of this species.<br />

Size. -This species exhibits strong sexual dimor-<br />

phism with males reaching larger adult size (maxi-<br />

mum observed SVL = 125 mm) than females (max-<br />

imum observed SVL = 98 mm).<br />

Distribution (Fig. 48). - Crotaphyrus vestigium in -<br />

habits the peninsular ranges and adjacent rocky hab-<br />

itats from the northern slope of the San Jacinto<br />

<strong>Mountain</strong>s in southern California to the southern<br />

margin of the volcanic Magdalena Plain in Baja Cal-<br />

ifornia Sur. In southern California and northern Baja<br />

California, C. vestigium is limited to the eastern face<br />

of the peninsular ranges. There is a gap in the pen-<br />

insular ranges between the southern edge of the Si-<br />

erra San Pedro Martir and the northern edge of the<br />

Sierra La Asamblea and C. vstigiurn occurs on ei-<br />

ther side of the peninsular ranges from this point<br />

southward. Furthermore, its range extends nonh-<br />

ward along the western side of the peninsular ranges<br />

from this gap to a point at least as far north as the<br />

vicinity of Rancho San Jose (Meling's Ranch) and<br />

even approaches the Pacific Coast at Mesa San Car-<br />

los (Bostic, 1971). The known southern distribu-<br />

tional limit of C. vestigiunr is 27.7 km (by road) S<br />

of San Jose de Comondu (McGuire, 1991). It is<br />

likely that the actual distributional limit is bounded<br />

by the volcanic mesas that terminate near this locality.<br />

Crotaphyttcs vestigittm apparently does not<br />

inhabit the isolated Sierra Santa Clara and Sierra<br />

Vizcaino on the Vizcaino Peninsula (Grismer et al.,<br />

1994).<br />

Fossil Record. -None.<br />

Narrtral History. -Very little has been written regarding<br />

the natural history of Crotaphytus vestigium.<br />

Sanborn and Loomis (1979) discussed the display<br />

patterns for this species and noted that it inhabits<br />

rocky outcroppings on the more rugged portions of<br />

the alluvial fans and mountain slopes at their San<br />

Jacinto <strong>Mountain</strong>s study site. Common plant species<br />

at this locality included Larrea tridenrara, Encelia<br />

Jarinosa, and Ambrosia dumosa. Welsh ( 1 988)<br />

collected two individuals, one of which was found<br />

on a rocky volcanic slope in central desert scrub and<br />

the other on a granitic outcrop in coastal sage scrub.<br />

Bostic (1 97 1) observed two individuals on Mesa San<br />

Carlos, a table-topped mountain overlooking the<br />

Pacific coast of Baja California approximately 350<br />

km south of the United States-Mexico border. One<br />

of these individuals was foraging among large basaltic<br />

rocks along the edge of the mesa while the<br />

other was seen basking on a large basaltic outcropping<br />

on top of the mesa proper.<br />

Crotaphytus vestigiurn is a denizen of desert hillsides,<br />

alluvial fans, canyons, and lava flows, always<br />

in association with rocks. They occur in some of the<br />

most xeric habitats of Nonh America such as the<br />

eastern bases of the Sierra de Juarez and Sierra San<br />

Pedro Martir where they may be observed basking<br />

during the heat of the day. The rocky habitats in<br />

which they occur generally are characterized by scant<br />

vegetation. Common plant taxa with which C. vestigiu~n<br />

is often associated include Fouquieria splendens,<br />

F. diguni, Opunria, Larrea tridenfata, Pachycormus<br />

discolor, Bursera, Ferocacrus, Pachycereus<br />

pringlei, Prosopis, and numerous additional xerophilic<br />

species. When alarmed, this species can move<br />

with great speed over complex rocky terrain by<br />

bounding bipedally from one stone to the next, often<br />

taking refuge beneath a larger rock.<br />

The activity season for adult Crotaphyttcs vestigium<br />

probably commences in March. Adults have<br />

been observed as early as 1 April 1992 at the foot<br />

of the Sierra La Asamblea, Baja California, and adult<br />

males, gravid females, and subadults have been

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