Geographic Variation in the Pocket Gopher, Thomomys bottae, in Colorado

by Phillip M. Youngman

Variation is slight in the large series of topotypes of T. b. internatus. Specimens from other localities in the western part of the range differ little from the topotypes. Specimens from one mile west of Coaldale have slightly more inflated bullae that are more flattened ventrally. Specimens from five miles south of Cotopaxi also have the bullae more flattened ventrally.

Specimens from localities bordering the plains differ from the topotypes and near topotypes, and in general show greater variation from locality to locality. Specimens from 12 miles north of Cañon City are dark, resembling T. b. rubidus, but cranially agree with specimens from near Colorado Springs in being indistinguishable from specimens from Salida. Specimens from St. Charles Mesa and Bear Creek near Walsenburg differ from the topotypes in having wider rostra. The specimens from St. Charles Mesa have more inflated bullae.

Specimens examined.—Total 93. Chaffee Co.: 2 mi. NNW Salida, 7100 ft., 3; Salida, 28 (20 ERW, 8 USNM). Fremont Co.: 12 mi. N Cañon City, 5; 1 mi. W Coaldale, 8; Cotopaxi, 1 (CSU); 5 mi. S Cotopaxi, 12. El Paso Co.: 1-1/4 mi. S Colorado Springs, 2; 9 mi. SSW Colorado Springs, 2; 17 mi. S Colorado Springs, 1. Custer Co.: 2-1/2 mi. S Wetmore, 3; Santa Fe Drive and 20th Lane, Blende, 1; St. Charles Mesa, 5600 ft., 2 (CSU); Fork of Huerfano and Cucharas rivers, 2 (CMNH). Huerfano Co.: 11 mi. WNW Gardner, 7000 ft., 3; Gardner, 7000 ft., 2 (USNM); 1-1/2 mi. S Redwing, 3; Bear Creek, near Walsenburg, 2 (CSU); 1 mi. E La Veta, 8; 5 mi. SE La Veta, 2.

Thomomys bottae cultellus Kelson

Thomomys bottae cultellus Kelson, Univ. Kansas Publ., Mus. Nat. Hist., 5:64, October 1, 1951.

Thomomys fulvus, Cary, Proc. Biol. Soc. Washington, 20:26, March 27, 1907; Warren, Colorado College Publ., 33:76, January, 1908; Warren, Mammals of Colorado, p. 80, 1910.

Thomomys fulvus fulvus, Bailey, N. Amer. Fauna, 39:80, November 15, 1915.

Holotype.—Adult male, skin and skull, number 70919, United States National Museum, Halls Peak, Mora County, New Mexico; January 13, 1895, obtained by C. Barber.

Distribution.—Raton Section of the Great Plains in northern New Mexico and extreme southern Colorado (see fig. 1).