Morphometric analysis of seven species of pocket gophers (geomyidae)

Pocket gophers of the genus Geomys (Mammaha, rodentia) are fossorial rodents that are restricted geographically to North and Central America (Hall, 1981) Thirty-eight species and subspecies of Geomys have been recognized from this region (Davis, 1940; Hart, 1978; HaU, 1981). Of this group, G. arenahus, G. attwateri, G. breviceps, G. bursarius, G. knoxjonesi, G. personatus, and G. texensis occur in the southwestern United States. The distribution and diversity of this genus reaches a maximum in the state of Texas where all seven species occur. Consequently, this region (Texas) has received much of the focus of systematic and taxonomic questions.

The distribution of members of this genus encompasses all four of the ecological regions of Texas as depicted in Davis and Schmidly (1994). These distributions in Texas can be described as endemic (G. attwateri, G. personatus, and G. texensis), allopatric (G. arenarius), and parapatric (G. attwateri diid G. breviceps, G. attwateri and G. personatus, G. attwateri and G. texensis, G. bursarius and G. breviceps, and G. bursarius and G. knoxjonesi). In addition, sympatric distributions have been identified in the contact zone studies of G. attwateri and G. breviceps (Tucker and Schmidly, 1981; Burton and Bickham, 1989; Dowler, 1989). Specifically, the distributions are as follows. Geomys arenahus is found only in the western Trans-Pecos region along the Rio Grande Valley. The range of G. attwateri includes central Texas west of the Brazos River, south to the San Antonio River, and along the central Gulf coast. Geomys breviceps occurs in the eastern portion (east of the Brazos River) of Texas. Geomys bursarius is located in northwestern and north-central Texas. Geomys knoxjonesi inhabits the deep sandy soils of the southwestern plains of Texas and eastern New Mexico. Geomys personatus occurs throughout most of south Texas, and G. texensis occurs only in two isolated areas of the Texas Hill Country.