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74 BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32
Fig. 44.-Geographic distribution of Crotaphytw bicinctores. The
"?" near Flagstaff denotes a questionable record for the species
at Williams, Arizona. The "?" in central Utah represents two
records from Emery County that could not be precisely located:
Nine miles W of Hanksville Highway at Nixon Uranium Mine
and the Mamie Stover Incline.
ifornia, western and northern Arizona, southeastern
Oregon, western Idaho, western and central Utah,
and much of Nevada. In Idaho, the species occurs
primarily in association with the Snake River drain-
age. Two additional localities in Idaho (approxi-
mately 24 km NNE of Atomic City, Butte County,
and Montpelier, Bear Lake County) are not indi-
cated on the Crotaphytus bicinctores distribution map
(Fig. 44) but may represent relict populations. There
is a series of three specimens in the Museum of
Vertebrate Zoology (MVZ 434 15-1 7) listed as col-
lected at Cheney, Spokane County, Washington. This
disjunct locality should be considered questionable
until verified by additional field work.
In southwestern Arizona, the species occurs
throughout the volcanic mountain ranges north of
the Gila River, while C. nebrius occupies most of
the mountain systems south ofthe Gila River. How-
ever, C. bicinctores occurs south of the Gila River
near the town of Sentinel, a locality that is not oc-
cupied by C. nebrius. In at least two localities, C.
bicinctores and C. nebrius are only narrowly sepa-
rated by the Gila River. Crotaphytus bicinctores oc-
curs in the Laguna Mountains which lie on the north
side of the Gila River, while C. nebrius occurs in
the Gila Mountains on the south side of the Gila
River. Also, C. bicinctores occurs in the Gila Bend
Mountains on the west shore ofthe Gila River, while
C. nebrius occurs in the Buckeye Hills on the ad-
jacent east shore. I observed a subadult C. bicinc-
tores at Black Gap, Maricopa County, Arizona, a
narrow pass on the western periphery ofthe Sauceda
Mountains through which Arizona State Highway
85 passes. This observation was extremely surpris-
ing given that this area is apparently well isolated
from known C. bicinctores populations north of the
Gila Bend River and on the Sentinel Plain. If C.
bicinctores has an established population at this lo-
cality, it is likely that C. nebrius and C. bicinctores
contact somewhere in the Sauceda or Maricopa
mountains. Several later attempts to find C. bicinc-
rores or C. nebrius at this locality were unsuccessful.
In northern Arizona, C. bicinctores occurs within
and north of the Colorado River drainage (Grand
Canyon) and follows the Little Colorado River
drainage as well. Over much of this area, the species
occurs in close geographic proximity to C. collaris.
Two hybrid zones between these species have been
documented based on morphological and electro-
phoretic evidence (Axtell, 1972; Montanucci, 1 983),
although it seems likely that additional contact zones
exist. The symbol "?" west of Flagstaff on Figure 44
represents a series of specimens (SDSNH 19474-
80) that includes both C. bicinctores and C. collaris.
It seems likely that the locality data for the C. bi-
cinctores in this series is incorrect.
In Utah, Crotaphytus bicinctores occupies most
of the desert mountain ranges west of the Wasatch
Range and also appears to occupy the arid regions
to the east of the Wasatch Range. The symbol "?"
on the C. bicinctores map (Fig. 44) represents two
localities in Emery County (9 mi W of Hanksville
Highway (Hwy 24) near the Nixon Uranium Mine
(BYU 16496) and the Mamie Stover Incline [BYU
20089-901) that are represented by specimens, but
for which I could not find the specific localities on
topographical maps.
Fossil Record. -Pleistocene fossils collected from
Rampart Cave, Arizona (Van Devender et al., 1977),