The pocket gophers of the species Thomomys talpoides in east-centralColorado have long been referred to the subspeciesThomomys talpoides clusius Coues with type locality at BridgerPass, Wyoming. Recently, two subspecies, T. t. attenuatus andT. t. rostralis (see Hall and Montague, Univ. Kansas Publ., Mus.Nat. Hist., 5(3):25-32, February 28, 1951) were named from alongthe Wyoming-Colorado boundary with the result that the populationsof Thomomys talpoides in east-central Colorado are separatedfrom T. t. clusius of Wyoming by the geographic ranges nowascribed to the recently named T. t. attenuatus and T. t. rostralis.The subspecific identity of the animals from east-central Coloradothus is left in doubt. Examination of pertinent materials was madein the expectation that the names Thomomys talpoides macrotisF. W. Miller (Proc. Colorado Mus. Nat. Hist., 9:41, December 14,1930) and Thomomys talpoides cheyennensis Swenk (MissouriValley Fauna, 4:5, March 1, 1941) would apply to the specimens,the identity of which is in doubt. This examination discloses instead,as set forth in more detail below, that neither of the twonames mentioned immediately above does apply; the Coloradanspecimens in question are referable to an heretofore unrecognizedsubspecies which may be named and described as follows:
Thomomys talpoides retrorsus new subspecies
Thomomys clusius, Warren, The Mammals of Colorado, G. P. Putnam'sSons, New York, p. 80, 1910; Cary, N. Amer. Fauna, 33:132,August 17, 1911.
Thomomys talpoides clusius, Bailey, N. Amer. Fauna, 39:100, November15, 1915; F. W. Miller, Proc. Colorado Mus. Nat. Hist., 9:41,December 14, 1930; Warren, The Mammals of Colorado, Univ. OklahomaPress, Norman, p. 162, 1942.
Type.—Male, subadult, skull and skin, No. 69840 Biological Surveys Collection,U. S. Nat. Hist.; from Flagler, Kit Carson County, Colorado; obtainedon November 26, 1894, by Clark P. Streator; original No. 4460.
Range.—Western end of the Arkansas Divide in Colorado from eight milessouth of Seibert westward to Colorado Springs[Pg 84]
Diagnosis.—Size medium (see measurements); upper parts grayish brown;underparts lighter; skull small; tympanic bullae moderately inflated andangular anterolaterally; interpterygoid space narrowly U-shaped; pterygoidhamuli without transverse enlargement; nasals truncate posteriorly; premaxillarytongues projecting posteriorly behind nasals for distance of eight-tenths(0.5-1.1) of a millimeter.
Comparisons....