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McGUIRE- SYSTEMATICS OF CROTAPHYTID LIZARDS 7 7
pale to fluorescent. The white component of the
dorsal pattern is retained well in preservative and
is easily characterized as nearly all populations have
white spots on the body with spots or reticulations
present on the tail and hindlimbs. Some populations
from Coahuila, Durango, Nuevo Leon, San Luis
Potosi, and Zacatecas may have a dorsal pattern
consisting at least in pan of black spots that may or
may not be surrounded by white, a pattern that is
reminiscent of that of C. antiquus and C. reticulatus
and potentially the result of introgression from the
latter species (Montanucci, 1974). The forelimbs are
generally patternless or only obscurely patterned,
but may occasionally bear pale reticulations or spots.
Transverse body bars are absent. Reticulations gen-
erally are confined to the superficial mandibular and
temporal regions, as well as the hindlimbs and tail.
A broad white or off-white caudal vertebral stripe
is lacking. The dorsal surface of the head is not pale-
colored, and generally is covered with spots that
range in color from rust to chocolate brown. Olive
green or orange ventrolateral coloration is lacking.
Most of the variation in gular pattern coloration
observed within Crotaphytus is restricted to C. col-
laris. The gular coloration observed in living adult
males examined over the course of this study range
between olive green, dark blue, turquoise blue, slate
gray, yellow, or orange. However, a black central
component is not found in this species. As stated
above, the peripheral gular pattern is always com-
posed of a white reticulated pattern. Anterior and
posterior collar markings are always present and the
posterior markings occasionally may contact mid-
dorsally. The anterior collars are not complete ven-
trally as black pigments are absent from the gular
fold. A pair of black spots may be present middor-
sally between the anterior collar markings. A pair
of enlarged melanic axillary patches are variably
present immediately posterior to the forelimb in-
sertion, although they are restricted to populations
from the western portion of the species' range (Ar-
izona). Small melanic inguinal patches are also vari-
ably present in adult males from this portion of the
range. The femoral pores are generally off-white to
gray in color. Paired, melanic keels may or may not
be present on the ventral surface of the caudal ex-
tremity.
Female Crotaphytus collaris are much less con-
spicuously marked than males, particularly in those
populations characterized by green dorsal colora-
tion. While females may retain a green component
in their pattern, it is always of a much duller hue.
As in other Crotaphyrw. the gular pattern of females
is less developed. Inguinal patches, which are vari-
ably present in adult males, are lacking in females.
Females develop vivid orange or reddish lateral bars
during the gravid period. The tail is not vividly
colored in either adult or subadult females.
Size. -This species exhibits strong sexual dimor-
phism with males reaching larger adult size (maxi-
mum observed SVL = 13 1 mm) than females (max-
imum observed SVL = 106 mm).
Distribution (Fig. 45). - Crotaphytus collaris has
an extensive distribution in the western and south-
central United States and northern Mexico extend-
ing from northwestern Arizona, eastern Utah, and
western Colorado eastward across the southern Great
Plains into Missouri, northern Arkansas, and pos-
sibly extreme northwestern Louisiana; and south-
ward into extreme nonhern Sonora and nonhcen-
tral mainland Mexico. Numerous isolated popula-
tions occur on the eastern periphery of its range in
Missouri and Arkansas. In Texas, the eastern dis-
tributional extent of C. collaris is limited by the
Balcones Escarpment as suitable rocky habitat does
not extend east of this point. For this reason, a num-
ber of localities that lie east of the escarpment are
considered questionable (FMNH 1 1 7 1 16-1 8 -"Ce-
dar Creek, Bastrop Co."; USNM 12762-"Tehu-
acana, Limestone Co.," 145 18 -"Gainesville, Cooke
Co."; UTA 892-"10 mi. S Dallas, Dallas Co."; see
Axtell [1989a] for a more complete assessment of
potentially erroneous localities for Texas speci-
mens). In Mexico, C. collaris extends as far east as
the eastern slopes of the Sierra Madre Oriental, while
C. reliculatus occupies the flatland Tamaulipan
thornscrub habitats to the immediate east. These
two species approach one another closely in the vi-
cinity of Allende, Coahuila, Mexico. In western and
northern Arizona, the distributions of C. collaris
and C. bicinctores abut one another and at least two
hybrid zones occur (see description of the distri-
bution of C. bicincrores). The questionable ("?")
Colorado locality on the dot distribution map (Fig.
45) refers to a specimen (USNM 58603) from Ar-
chuleta County, Colorado, for which no specific lo-
cality data were given. The questionable ("?') 10-
cality from near the border between Tamaulipas and
San Luis Potosi, Mexico, represents a locality given
for C. rcticulatus (AMNH 104448-"rte. 101, 12
mi. SW jct. with side rd. to Tula, 13 mi. NE San
Luis Potosi state line"). This locality is dubious for
C. reticularus, but would not be unexpected for C.
collaris.
An extremely detailed dot distribution map for
C. collaris in Texas was provided by Axtell (I 989a).