University of Kansas Publications
Museum of Natural History

Volume 14, No. 8, pp. 121-124
March 7, 1962


A New Subspecies of Ground Squirrel
(Spermophilus spilosoma) from Tamaulipas,
Mexico

BY

TICUL ALVAREZ

University of Kansas
Lawrence

1962

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.

Volume 14, No. 8, pp. 121-124
Published March 7, 1962

University of Kansas
Lawrence, Kansas

PRINTED BY
JEAN M. NEIBARGER, STATE PRINTER
TOPEKA, KANSAS
1962



29-1505


[123]

A New Subspecies of Ground Squirrel
(Spermophilus spilosoma) from Tamaulipas,
Mexico

BY TICUL ALVAREZ

When A. H. Howell (N. Amer. Fauna, 56:1-256, 1938) revisedthe North American ground squirrels, he had no specimens of thespotted ground squirrel, Spermophilus spilosoma, from Tamaulipas.Thirteen years later, Hall (Univ. Kansas Publ., Mus. Nat. Hist., 5:38,1951) listed the species for the first time from the state when herecorded as S. s. annectens 13 specimens from the barrier beach88-89 miles south and 10 miles west of Matamoros.

In 1953, Mr. Gerd Heinrich collected 10 individuals of S. spilosomafrom the coastal plain of eastern Tamaulipas that extendsouthward the known range of the species on the east coast ofMéxico, provide the first specimens from the mainland of Tamaulipas,and represent a new subspecies that is named and describedbelow.

Spermophilus spilosoma oricolus new subspecies

Type.—Female, adult, skin and skull, No. 55497 Museum of Natural History,The University of Kansas; from one mile east of La Pesca, Tamaulipas, México;obtained on May 27, 1953, by Gerd Heinrich, original number 6933.

Diagnosis.—Size medium for species (see measurements); general colorcinnamon buff, almost pure on dorsal surface of hind foot and dorsal and ventralmidline of tail; spots well marked; postorbital constriction narrow; auditorybullae small; viewed from front, lower border of maxillary plate forming continuouslyconcave line with jugal; zygomatic process of maxillary narrow, havinganterior border concave.

Comparisons.—From Spermophilus spilosoma annectens (specimens fromPadre and Mustang islands, Texas), S. s. oricolus differs as follows: larger inexternal dimensions but smaller in cranial dimensions; postorbital constrictionnarrower, 13.4 (13.2-13.8) instead of 14.0 (13.5-14.7); rostrum slightlybroader; greatest distance between posterior border of maxillary plate andsquamosal arm of zygoma longer, averaging 9.9 (9.7-10.2) instead of 9.6(9.0-10.1); zygomatic process of maxillary, viewed dorsolaterally above lacrimalnarrower, having anterior border concave instead of almost straight; when skullviewed from front, lower border of maxillary plate forming continuously concaveline with jugal instead of almost a right angle where jugal and maxillarymeet; ramus of lower jaw narrower; general color paler; upper surface of hindfoot washed with cinnamon instead of yellowish; postauricular spot absent(usually present in annectens).

From Spermophilus spilosoma pallescens (specimens from southeasternCoahuila), S. s. oricolus differs as follows: color more cinnamon especially o

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