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80 BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32
ranges of these subspecies, as they are currently con-
strued, are not consistent with these color pattern
concepts. Crotaphytus c. baileyi, whose recognized
range has been fragmented over the years by the
descriptions of C. c. auriceps, C. c. fuscus, and C. c.
melanomaculatus, is thought to extend from west-
em Arizona, eastward through central New Mexico,
and southward through the panhandle of Texas into
northcentral Mexico. The currently recognized dis-
tribution of C. c. baileyi makes little sense when one
considers that individuals from the Big Bend region
(C. c. baileyi) may appear phenotypically identical
to those from the Organ Mountains of New Mexico
(C. c. fuscus). Thus, the subspecies of C. collaris do
not appear to be on separate phylogenetic trajec-
tories and do not even seem to represent useful pat-
tern classes.
Crotaphytus dickersonae Schmidt
(Fig. 31B, C)
Crotaphytus dickersonaeSchmidt, 1922638; fig. 2. Type locality:
lsla Tiburon, Gulf of California, Mexico (holotype: USNM
6445 I).
Crotaphyrus colloris dickersonae- Allen, 1933:7.
Crotaphyrus (Croraphytus) collaris dickersonae- Wcincr and
Smith, 1965:187.
Etymology.-Named in honor of Mary C. Dickcrson, former
curator of herpetology at the American Museum of Natural His-
tory, who studied the insular herpetofauna of the Gulf of Cali-
fornia, Mexico.
Diagnosis. - Crotaphytus dickersonae can be dis-
tinguished from Crotaphytus bicinctores, C. gris-
meri, C. insularis, and C. vestigium by the presence
of black oral melanin, a blue or turquoise dorsal
coloration, and the absence of enlarged postanal
scales in males. It may be distinguished from C.
reticulatus, C. collaris, and C. nebrius by the pres-
ence in adult males of a strongly laterally com-
pressed tail with a white or pale stripe extending
vertebrally and enlarged dark brown or black in-
guinal patches extending between one-half and one-
third of the distance between the hindlimb and fore-
limb insertions. It may be further distinguished from
C. reticulatus and C. anriquus by the presence of a
dorsal pattern of white spots on a blue or turquoise
field rather than white reticulations on a gold, tan,
or brown field. It may be further distinguished from
C. collaris by the presence of dark brown or black
pigmentation in the gular fold (= ventrally complete
anterior collar) and the absence of enlarged postanal
scales in males. It may be further distinguished from
C. nebrius by the presence of a blue or turquoise
dorsal coloration rather than tan and the absence of
enlarged postanal scales in males.
Variation (n = 20).-Rostra1 approximately two
times wider than high, usually rectangular in shape.
Rostra1 bordered by two to four postrostrals. Re-
maining snout scales irregularly arranged, an en-
larged middorsal series may be present. Nasals sep-
arated by four to six intemasals. Frontonasals oc-
casionally enlarged. Canthals three; four to seven
scales separate canthals of left and right sides. Su-
praorbital semicircles present with 1 1 to 15 scales
per semicircle, median scales do not fuse to form
azygous frontals. Supraoculars flat or convex,
smooth, becoming progressively larger medially such
that medial scales are two to four times larger than
lateral ones. Circumorbitals present, not well dif-
ferentiated from supraoculars. Superciliaries eight
to 12, extremely elongate medial scale absent. Pal-
pebrals ovoid, slightly convex, interspersed with nu-
merous interstitial granules. Preoculars, suboculars,
and postoculars form an arc of six to nine rectan-
gular scales, second, third, or fourth scale not elon-
gate. Supralabials 13 to 17, usually slightly longer
than high except anteriormost scale, which is square
or pentagonal. Lorilabials in two to four rows, ovoid
to rectangular, juxtaposed, separating supralabials
from suboculars and nasals. Aperture of external
auditory meatus rectangular or ovoid, often con-
stricted at or above the midpoint, approximately
two to four times higher than wide, with small,
strongly convex, somewhat conical auricular scales
lining anterior margin. Mental pentagonal, one to
1.5 times wider than high, bordered laterally by an-
terior infralabials and posteriorly by a pair of large
postmentals. Postmentals usually separated from
infralabials by a pair of sublabials; sublabials oc-
casionally absent on one or both sides. Chinshields
weakly differentiated or undifferentiated. Infrala-
bials ten to 16, square or wider than high, inferior
border convex. Gulars granular, strongly convex and
beadlike, each scale separated from adjacent scales
by numerous asymmetrically arranged interstitial
granules.
Dorsal scales in approximately 154 to 186 rows
midway between forelimb and hindlimb insertions.
Tail long, cylindrical to oval in females and juve-
niles of both sexes over entire length, anterior one-
half strongly laterally compressed in adult males.
Paired, median row of subcaudals larger than ad-