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University of Kansas Publications

Museum of Natural History

---

Vol. 10, No. 9, pp. 587-598, 2 figs.

  May 2, 1960  

 

 

 

A New Subspecies of Lizard,

Cnemidophorus sacki, from Michoacán, México

 

 

BY

 

WILLIAM E. DUELLMAN

 

 

 

 

 

 

University of Kansas

Lawrence

1960

 

 

[588]

University of Kansas Publications, Museum of Natural History


Editors: E. Raymond Hall, Chairman, Henry S. Fitch,

Robert W. Wilson

 

 

Volume 10, No. 9, pp. 587-598, 2 figs.

Published May 2, 1960

 

 

University of Kansas

Lawrence, Kansas

PRINTED IN

THE STATE PRINTING PLANT

TOPEKA, KANSAS

1960



28-2494

[589]

The systematic status of the populations of lizards assignable to
Cnemidophorus sacki in western México (Sonora southward to
Jalisco) has been reviewed in detail by Zweifel (1959, Bull. Amer.
Mus. Nat. Hist, 117 (2):57-116), who stated that the use of the
specific name sacki for the western populations rests upon a reasonable,
but as yet unproved, assumption that intergradation occurs.
Although Zweifel examined specimens of the nominal subspecies
from the upper Balsas Basin, he did not study specimens from the
intervening area—the Tepalcatepec Valley in Michoacán.

Field studies and the examination of large series of preserved
specimens of Cnemidophorus from the Tepalcatepec Valley show
the presence of Cnemidophorus sacki in the region between the
ranges of C. sacki sacki in the upper Balsas Basin and C. sacki
occidentalis in Jalisco and southern Nayarit. Furthermore, the
populations of sacki inhabiting the Tepalcatepec Valley have characters
of scutellation and coloration that distinguish them from
other described subspecies of sacki. In recognition of the important
contributions to the systematics of the genus Cnemidophorus made
by Dr. Richard G. Zweifel, I propose that the subspecies of Cnemidophorus
sacki in the Tepalcatepec Valley be named as follows:

[590]

Click on image to view larger sized version.


Fig. 1. Top view of the head of the holotype of Cnemidophorus sacki
zweifeli (UMMZ 119542) showing scutellation.

[591]

Ontogenetic Change in Color Pattern.—The metamorphosis of
color pattern in Cnemidophorus sacki zweifeli results in the dorsal
ground-color becoming paler with age, the replacement of the
stripes by spots, and finally in large males the suffusion of these
spots.

A single hatchling (UMMZ 114732) is available; this specimen
has a prominent umbilical scar and a snout-vent length of 34 mm.
The top of the head is olive brown; the dorsal surfaces of the limbs
are dark brown with cream mottling; the dorsal ground-color is
brownish black; this is paler on the lower flanks. The lateral and
dorsolateral stripes are cream-colored; the paravertebral stripes are
[592]
white. There is a faint, diffuse vertebral stripe anteriorly (Fig. 2 A).
The throat and undersides of the limbs and tail are cream-colored;
the belly is bluish white. In life the stripes were pale yellowish
green, and the tip of the tail was pink.

In larger individuals the dorsal ground-color is dark brown; the
lower flanks are grayish tan. Light brown diffuse spots are present
in the lateral and dorsolateral dark fields. The tan vertebral stripe
is diffuse and nearly fills the paravertebral dark fields; the paravertebral
stripes are faint posteriorly; throughout their length they are
scalloped—the beginning of their fragmentation into spots (Fig.
2 B).

In subadults (± 80 mm. snout-vent length) the paravertebral
stripes are fragmented into spots posteriorly. Also, the dorsolateral
stripes in some individuals are fragmented posteriorly. The dorsolateral
dark fields are somewhat paler than the lateral dark fields.
Cream-colored spots are present on the flanks. The mottling on
the thighs tends towards the formation of light spots (Fig. 2 C).

In small adults (± 100 mm. snout-vent length) the paravertebral
stripes are entirely fragmented into spots. The lateral and dorsolateral
stripes are broken into spots posteriorly. The middorsal pale
area (formed by the suffusion of the vertebral stripe) and paravertebral
and dorsolateral rows of spots are pale green. The cream-colored
spots on the flanks are expanded to form vertical bars
(Fig. 2 D).

Large adult males (± 120 mm. snout-vent length) have all of
the stripes fragmented into spots. The diffuse middorsal area is
expanded and encloses the paravertebral rows of spots. The pale
spots present in the dark fields in smaller individuals are either
absent or fused with spots resulting from the fragmentation of the
stripes (Fig. 2 E).

Sexual dimorphism.—Males attain a larger size (known maximum
snout-vent length of 132 mm., as compared with 114 mm. in females).
Males have larger but not more numerous, femoral pores,
blue bellies, and pink and blue throats, whereas females are unicolor
creamy white ventrally. The more nearly complete metamorphosis
of color pattern exhibited by adult males probably is
correlated with their large adult size. Large females retain complete
lateral and dorsolateral stripes. The jowls of breeding males
are swollen.

[593]

Click on image to view larger sized version.

Fig. 2. Diagrammatic representation of ontogenetic change in color pattern in Cnemidophorus sacki zweifeli: A—hatchling, 34
mm. snout-vent length; B—juvenile, 55 mm. snout-vent length; C—subadult male, 80 mm. snout-vent length; D—small adult male,
100 mm. snout-vent length; E—large adult male, 120 mm. snout-vent length.

[594]

Geographic variation.—No noticeable geographic variation in
this subspecies is evident in the series from the Tepalcatepec
Valley. However, lizards from eastern Michoacán (Chinapa, 6
km. N of Tafetan, 6 km. S of Tzitzio, and 19 km. S of Tzitzio) differ
slightly from those from the Tepalcatepec Valley; the eastern
specimens have fewer dorsal granules and femoral pores, and a
higher ratio of dorsal granules between the paravertebral stripes
to the number of granules around the body (see Tables 1-3). No
large adult males are present in the eastern series; the subadults
and small adult males have color patterns like lizards of similar
size from the Tepalcatepec Valley. The largest male from the east
has a snout-vent length of 110 mm., rows of pale spots, and no trace
of brown and tan cross-bars. Specimens of Cnemidophorus sacki
sacki of equal size from Guerrero, Morelos, and Puebla in the upper
Balsas Basin have a tan dorsum with dark brown cross-bars. The
localities in eastern Michoacán are intermediate geographically
between the Tepalcatepec Valley and the known range of the
nominal subspecies in the upper Balsas Basin. In characters of
scutellation specimens from the east are intermediate between C.
sacki sacki and C. sacki zweifeli in the Tepalcatepec Valley. However,
in coloration the lizards from the east are like those from the
Tepalcatepec Valley, but differ distinctly from the nominal subspecies.
Therefore, the eastern series is referred to the subspecies
C. sacki zweifeli.

Comparisons.—Four other species of Cnemidophorus occur in
the Tepalcatepec Valley with Cnemidophorus sacki zweifeli. Of
these, C. calidipes has a maximum snout-vent length of 79 mm., 66
to 86 dorsal granules, and a light brown dorsum with pale blue
spots and vertical bars; C. communis communis has a maximum
snout-vent length of 135 mm., 105 to 144 dorsal granules, and a
greenish tan dorsum with yellow spots; C. deppei infernalis has a
maximum snout-vent length of 84 mm., 91 to 120 dorsal granules,
and a striped pattern throughout life; and C. lineatissimus exoristus
has a maximum snout-vent length of 98 mm., 108 to 135 dorsal
granules, and a middorsal yellow stripe and vertical bars on the
flanks. Both calidipes and communis are like sacki in possessing
four enlarged supraoculars and enlarged postantebrachials, whereas
deppei and lineatissimus have three enlarged supraoculars and
granular postantebrachials. Juveniles of calidipes and sacki are
alike in coloration but different in the extent of the supraorbital
semicircle-series. In calidipes the supraorbital semicircle-series usually
are complete, whereas in sacki the series never extended anterior
to the posterior edge of the frontal.

[595]

[596]

From the geographically adjacent populations of sacki (sacki and
occidentalis), zweifeli differs in coloration and scutellation (see
Tables I-III). Cnemidophorus sacki sacki has a dorsal pattern in
adult males of dark brown cross-bars on a tan ground-color. Both
occidentalis and zweifeli have variable, diffuse color patterns in
large adults, but zweifeli differs from occidentalis in having a blue
spot on the pink throat.

Ecology.—In the arid Tepalcatepec Valley Cnemidophorus sacki
zweifeli lives at elevations of 160 to 1300 meters. In the lower parts
of the valley the lizards live primarily in open scrub forests, characterized
by deciduous trees offering only partial shade from the
sun, especially during the prolonged dry season. Common trees in
this scrub forest are Acacia cymbispina, Cercidium plurifoliolatum,
Mimosa distachya, and Prosopis juliflora.

During the dry season (November through May) adult males
apparently aestivate; several large series collected in the winter
include only subadults and females. This absence of males is
corroborated by personal observations in the Tepalcatepec Valley
in April and May. In the summer rainy season the lizards are active
in the morning and again in the late afternoon; only Cnemidophorus
calidipes is active during the heat of the midday. In some
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areas of the scrub forest Cnemidophorus sacki zweifeli is found in
association with Cnemidophorus communis communis. Throughout
the scrub forest C. sacki zweifeli occurs with C. deppei infernalis.
In some of the more dense scrub forest, where C. sacki zweifeli
is not so abundant as in the more open forest, it has been taken
with C. lineatissimus exoristus. In the open Acacia-Cercidium associations
on the valley floor C. sacki zweifeli occurs with C. calidipes.

This subspecies is not restricted to the scrub forest. On the
lower slopes of the Cordillera Volcanica in Michoacán C. sacki
zweifeli has been collected in open pine-oak forest near Zirimicuaro
and Ziracuaretiro.

Distribution.—Cnemidophorus sacki zweifeli inhabits the valley
of the Río Tepalcatepec in Michoacán and probably extreme southwestern
Jalisco, and the western part of the Balsas Basin in
Michoacán. No specimens have been seen from extreme western
Guerrero, but C. s. zweifeli may occur there.

Transmitted February 2, 1960.

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