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McGUIRE-SYSTEMATICS OF CROTAPHYTID LIZARDS
pale tan or green hues. Head coloration in males
may differ from that of the body, most notably in
those populations of C. collaris characterized by a
pale yellow to fluorescent yellow head. A pattern of
white reticulations is a recurring phenomenon with-
in the genus and may be present over the entire
dorsal surface of the body and limbs, as well as on
the temporal and superficial mandibular regions or
some subset thereof. A number of species have a
dorsal body and limb pattern composed of white
spots or dashes rather than net-like reticulations,
and narrow, transverse dorsal bars may be present.
A broad white or off-white vertebral stripe may ex-
tend from the base of the tail posteriorly for most
of its length. The dorsal surface of the head may be
pale-colored, with a more or less patternless surface.
All Crotaphytus are characterized by a ventral col-
oration of white, off-white, or pale yellow, although
additional markings may be present. Olive green,
golden orange, or burnt orange ventrolateral col-
oration may be present in males as well. The tail
may or not be bright lemon yellow in adult females
or burnt orange in subadult females.
Gular coloration in adult males is highly variable
with olive green, gun-barrel blue, slate gray, dark
brown, dark blue, turquoise blue, yellow, or orange
all characterizing the adult males of certain popu-
lations. The gular region of females is generally white
or only faintly patterned. The gular coloration of
adult males may or may not include a black central
component. The pattern surrounding the gular re-
gion of adult males is also variable and may be
composed of pale reticulations, white spots on a sky
blue background, or radiating, obliquely oriented,
white lines.
Black is an important color component within the
genus with all species having some combination of
black markings. All Crotaphytus except some female
C. insularis and C. reticulatus have at least one pair
of black collar markings and most have two pairs.
The anterior and posterior collar markings are sep-
arated by a broad white bar that may or may not
be complete middorsally. The anterior pair of collar
markings contact ventrally through the gular fold in
adult males of some species. The posterior collar
markings may contact middorsally in some species
as well. A pair of black spots may be present mid-
dorsally between the anterior collar markings. A pair
of enlarged melanic axillary patches are variably
present immediately posterior to the forelimb in-
sertion in adult males of several species. Small or
large melanic inguinal patches are also present in
the adult males of several species. All Crotaphytus
neonates are characterized by a pattern of white
reticulations, some ofwhich enclose black pigments.
This pattern may or may not be retained into adult-
hood with little modification. The femoral pores are
generally off-white to gray in color but are black in
males of two species (C. antiquus and C. reticulatus).
Paired, melanic keels may or may not be present on
the ventral surface of the caudal extremity.
All Crotaphytus females develop "gravid color-
ation" in the form of red or orange lateral bars or
spots. A similar pattern develops in subadult males
of all Crotaphytus species.
Size. -All Crotaphytzrs exhibit sexual dimor-
phism wherein males are larger than females. Max-
imum adult sizes range from approximately 99 mm
SVL in C. grismeri to approximately 13 1 mm SVL
in C. collaris (C. reticulatus may reach 1 37 mm SVL;
Montanucci, 1976).
Distribution. -Western and southcentral United
States from southern Idaho and eastern Oregon
southward and eastward across the southern Great
Plains into Missouri, northwestern Arkansas, and
extreme northwestern Louisiana, southward into
southern Baja California and northcentral mainland
Mexico.
Fossil Record. -Numerous Pleistocene fossils
have been referred to the genus, all of which have
been placed within C. collaris or listed as C. sp.
(Estes, 1983). However, the localities from which
some of these specimens have been collected suggest
that a few of these fossils may be C. bicinctores and
C. nebrius (Brattstrom, 1954; Van Devender et al.,
1977; Van Devender and Mead, 1978). The frag-
mentary nature of most of the material renders spe-
cific identification on the basis ofcharacter evidence
impossible.
Crotaphytus antiguus Axtell and Webb
(Fig. 30D)
Cmaph)~!us anriquus Axtell and Webb. 1995: 1; fig. 1, 2. Type
locality: "2.1 km N-1.7 km E Vizcaya (2Se46'04'N-
103'1 1'48"W. el I I OOf m) in the Sierra Texas. Coahuila. Mexico"
(Holotype: UTEP 15900).
Et~~rnolog)~. -From the latin anfiquus. meaning old or of antiquity.
The name was chosen by the authors because it "incorporates
(their) interpretation regarding the probable ancientness
of the lizard."
Diagnosis. - Crotaphytus antigutcs can be distin-
guished from all other Crotaphytus by the presence
of gravid coloration that is limited to the anterior
15 to 50 percent of the portion of the abdomen
between the forelimb and hindlimb insertions and
a much larger total number of white reticulations