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1996 McGUIRE-SYSTEMATICS OF CROTAPHYTID LIZARDS 6 7
The presence of bright red or orange dorsal pig-
mentation makes gravid Crotaphytus conspicuous
at a time when crypticity presumably would be at
a premium. Therefore, it is likely that the coloration
provides some form of visual signal to predators or
conspecifics that provides a greater selective benefit
than cost to gravid females. The behavior of repro-
ductive females toward males changes dramatically
from submissive to aggressive soon after copulation,
and this corresponds with an intensification of the
coloration (Fitch, 1956; Clarke, 1965; Cooper and
Crews, 1988). Therefore, Clarke (1965) and Cooper
(1988) suggested that gravid coloration may act as
an inhibitor of male aggression. If this is the case,
subadult males with red or orange coloration po-
tentially could benefit by being allowed to forage
within adult male territories without being attacked.
Indeed, Gambelia are well known for their canni-
The following taxonomic accounts include: (1)
synonymies for each taxon name, (2) phylogenetic
definitions for the three clade names (Crotaphytidae,
Crotaphytus, and Gambelia) following the recommendations
of de Queiroz and Gauthier (1992),
(3) an etymology for each taxon, (4) a general description
of squamation for Crotaphytidae, (5) a
more specific description of squamation for each
species, (6) general descriptions of coloration in life
for Crotaphytus and Garnbelia, (7) more specific descriptions
of coloration for each species, (8) a detailed
summary of geographic distribution for the
genera and species (locality data used in producing
the distribution maps are available from the author
upon request), (9) a discussion of natural history
where appropriate, and (1 0) a remarks section under
each species account that includes references to illustrations,
as well as various additional comments.
The list of published illustrations may be complete
for the rarer taxa, but is certainly incomplete for
wide-ranging, common species such as C. collaris
and G. ~vislizenii. Natural history observations that
are not followed by a literature citation are my own.
Crotaphytidae Smith and Brodie, 1982
Crotaphytinae Smith and Brodie. 1982: 106. Typc genus: Cro-
taphytur Holbrook. 1842.
Crotaphytidae Frost and Ethcridge, 198936.
De3nition.-Crotaphytidae is here defined as a
node-based name for the most recent common an-
TAXONOMIC ACCOUNTS
balistic habits and such coloration in Crotaphytus
may limit predation on subadults by adult males.
Because females are generally allowed to set up ter-
ritories within male territories in many territorial
species (Stamps, 1977; noted in C. collaris by Fitch,
1956, and Yedlin and Ferguson, 1973), subadult
females potentially would benefit less by bearing red
or orange dorsal coloration. If this is the case in
Crotaphyttcs, the presence of bright red or orange
coloration in subadult females might more likely be
selected against (assuming the presence of vibrant
orange or red coloration leaves them more conspic-
uous to visually oriented predators such as raptors
and loggerhead shrikes). Although this hypothesis
is highly speculative, it is consistent with the idea
that gravid coloration has a functional value in fe-
males on which subadult males could also capitalize.
cestor of Crotaphytus and Garnbelia and all of its
descendants.
Description, -A description of the squamation of crotaphytids
is given here to provide a consolidated view of those features
common to the family. To prevent an unnecessary duplication
of information, only variable features will be discussed under the
separate species accounts. General color pattem descriptions are
provided under the generic accounts of Crotaphytus and Gambelia.
with more specific characterizations given under each species
account.
Dorsal cephalic scales smooth, convex, polygonal, occasionally
with numerous inconspicuous surface irregularities. Rostral approximately
two to four times wider than high, usually rectangular
in shape. Rostral bordered by two to eight postrostrals.
Remaining snout scales irregularly arranged, an enlarged middorsal
series may be present. Nasals form a thin-walled ring,
picrced centrally by external nares; narcs face laterally at a slight
dorsal angle; nasals separated by three to nine intemasals. Frontonasals
occasionally enlarged. Three or four canthals, posterior
one or two wider than high; four to ten scales separate canthals
of len and right sides; canthus rostralis forms prominent ridge.
Supraorbital semicircles present or absent; when present some
scales may fuse to form azygous frontals. Interparietal small,
approximately twice as long as wide, with opalescent "eye." Parietal~
generally small and irregular. Supraoculars small, flat or
convex, smooth, becoming progressively larger medially such
that medial scales are two to four times larger than lateral ones.
Circurnorbitals present or absent; when present not well differentiated
from supraoculars. Superciliarics six to 15, extremely
clongatc medial scale present or absent; anterior scales with oblique
sutures oriented posterodorsally, posterior scales with oblique
sutures oriented antcrodorsally. Palpcbrals ovoid, slightly convex,
may be interspersed with numerous interstitial granules.
Inner ciliaries deeper than wide, outer ciliaries of upper eyelid
usually projecting, anterior and posterior ones projecting slightly