Ammospermophilus interpres

Texas Antelope Squirrel
(*Ammospermophilus interpres*)
Texas Antelope Squirrel (Ammospermophilus interpres)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Sciuromorpha
Family:	Sciuridae
Subfamily:	Xerinae
Tribe:	Marmotini
Genus:	Ammospermophilus
Binomial details
	Ammospermophilus interpres (C. H. Merriam, 1890)
Other resources
	Full taxonomic details at MDD

The Texas Antelope Squirrel (Ammospermophilus interpres) is a ground squirrel found in rocky, arid grasslands and scrublands of New Mexico, west Texas, and north-central Mexico.

Description

From Best et al. (1990): "Ammospermophilus interpres has one white stripe bordered with blackish on each side of the body, no distinct head stripes, and hairs on the underside of the tail that are medially white (Anderson, 1972). The dorsum is finely grizzled gray, faintly tinged with vinaceous posteriorly, and suffused with pale fulvous over the nose. The shoulders, hips, and outer surface of fore and hind legs are ochraceous buff. There is a broad stripe of clear white on each eyelid and on each side of the back from shoulder to side of rump. The ventrum is silky whitish. The proximal one-third of the tail is concolor with the back and suffused with pale fulvous dorsally; the distal two-thirds is grayish black with a partly concealed submarginal black band and whitish border. Ventrally, the tail is white, with two complete black bands (the innermost concealed) and a whitish border."

Museum specimens

Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889.

External measurements

Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.

Part of range	Reference	Total length	Tail length	Hindfoot length	Ear length	Mass
Texas	Schmidly & Bradley (2016)	226	74	38		males: 104 (94–121); females: 104 (84–115)

Skull

Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Dorsal view of the skull.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Ventral view of the skull.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Lateral view of the skull.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Dorsal view of the mandible.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Lateral view of the left mandible.

Similar species

Comparison with Ammospermophilus leucurus

From Best et al. (1990): "Compared to A. leucurus, A. interpres is slightly smaller. The skull is much blockier in outline, with a heavier rostrum and more flattened braincase. Compared to the paler, reddish pelage of A. leucurus, that of A. interpres is uniformly dark, with no apparent rufous tint. Further, two distinct black bands are visible on the undersurface of the tail of A. interpres, in contrast to a single band visible in A. leucurus."

Texas Antelope Squirrel (Ammospermophilus interpres) photographed by Chris Harrison in Franklin Mountains State Park, Texas.
White-tailed Antelope Squirrel (Ammospermophilus leucurus) photographed by lonnyholmes in Clark County, Nevada.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889.
Holotype: USNM 17987/24898. Ammospermophilus leucurus cinnamomeus. Adult female. Echo Cliffs, Painted Desert, Coconino County, Arizona. Collected 22 September 1889.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889. Dorsal view of the skull.
Holotype: USNM 17987/24898. Ammospermophilus leucurus cinnamomeus. Adult female. Echo Cliffs, Painted Desert, Coconino County, Arizona. Collected 22 September 1889. Dorsal view of the skull.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, [El Paso County], Texas. Collected 10 December 1889. Lateral view of the skull.
Holotype: USNM 17987/24898. Ammospermophilus leucurus cinnamomeus. Adult female. Echo Cliffs, Painted Desert, Coconino County, Arizona. Collected 22 September 1889. Lateral view of the skull.

Comparison with Ammospermophilus harrisii

From Best et al. (1990): "Compared to A. harrisii, which is similar in dorsal coloration, A. interpres is most easily distinguished by the tail banding pattern: the undersurface of the tail of A. harrisii is gray or has a salt and pepper appearance due to multiple banding of the tail hairs. The skull of A. harrisii is slightly larger, with relatively larger auditory bullae (especially due to expansion of the anterior bullar cell), but the tail and hind limbs are proportionally smaller in A. harrisii. The baculum of A. interpres, compared to that of A. leucurus and A. harrisii, is wider, more fan-shaped, and has a more pronounced shaft angle (Hafner, 1981)."

Texas Antelope Squirrel (Ammospermophilus interpres) photographed by Chris Harrison in Franklin Mountains State Park, Texas.
Harris's Antelope Squirrel (Ammospermophilus harrisii) photographed by Craig Robson in Pima County, Arizona.
Holotype: USNM 18162/25060. Ammospermophilus interpres. Adult female. El Paso, El Paso County, Texas. Collected 10 December 1889.
Holotype: USNM 59869. Ammospermophilus harrisii saxicolus. Adult female. Tinajas Altas, Gila Mountains, Yuma County, Arizona. Collected 17 February 1894.

References

Anderson S. 1972. Mammals of Chihuahua: taxonomy and distribution. Bulletin of the American Museum of Natural History 148:149-410.

Best TL, Lewis CL, Caesar K, Titus AS. 1990. Ammospermophilus interpres Mammalian Species (365): 1–6. https://doi.org/10.1093/mspecies/365.1

Hafner DJ. 1981. Evolution and historical zoogeography of antelope ground squirrels, genus Ammospermophilus (Rodentia: Sciuridae). Unpublished Ph.D. dissertation, The University of New Mexico, Albuquerque, 225 pp.

Merriam CH. 1890. Descriptions of five new ground squirrels of the genus Tamias. North American Fauna 4:17-22.

Schmidly DJ, Bradley RD. 2016. The mammals of Texas. Austin (TX, USA): University of Texas Press.