The Baculum in Pocket Gophers of Southwestern Wyoming

Abstract

In southwestern Wyoming three subspecies of pocket gophers have been referred to the species Thomomys talpoides. A subspecies of tiny, brown individuals is known as Thomomys talpoides pygmaeus. Individuals of T. t. pygmaeus usually occur in arid, sage-covered soils in extreme western Wyoming and southeastern Idaho. T. t. ocius is a pale whitish gopher slightly larger than T. t. pygmaeus, and also usually occurs in arid, sage-covered soils in western Wyoming. T. t. bridgeri is a large, dark brownish gopher that usually occurs in soils along streams. T. t. bridgeri is sympatric with T. t. pygmaeus in extreme western Wyoming and southeastern Idaho; bridgeri also occurs together with T. t. ocius, the geographic range of which lies to the east of that of T. t. pygmaeus. Specimens of T. t. bridgeri have been taken within yards of specimens of the other two subspecies. T. t. ocius may occur together with T. t. pygmaeus in some places; in any event their geographic ranges meet with no examples of intergradation between the two kinds being known. Although interacting as good species, these three kinds of gophers are arranged as subspecies of T. talpoides because each is known or thought to interbreed with one or several other subspecies of T. talpoides (Davis, 1939:254; Durrant, 1952:169; Whitlow and Hall, 1933:256). Bacula of these three subspecies are here compared.