Llano Pocket Gopher
Order Rodentia : Family Geomyidae : Geomys texensis Merriam

Description. A cryptic species with G. bursarius and G. knoxjonesi. Morphologically, the Llano pocket gopher is slightly smaller than the plains pocket gopher but biochemical study is required to reliably separate the two. Dental formula as in G. bursarius.

Distribution in Texas. Occurs only in two isolated areas of the Texas Hill Country. Records are from McCulloch, San Saba, Mason, Llano, Gillespie, Uvalde, Zavala, and Medina counties.

Habits. The natural history of G. texensis is undoubtedly similar to that of G. bursarius. The Llano pocket gopher is found in deep, brown loamy sands or gravelly sandy loams and is isolated from other species of Geomys by intervening shallow, stony to gravelly clayey soils.

Five specimens in the Texas Cooperative Wildlife Collection at Texas A&M University, collected in Llano County in mid-March, were reproductively active when captured. One contained three embryos, one had two embryos, one was "inseminated," one was lactating, and the fifth was pregnant with "very small embryos." A sixth specimen from this area contained no embryos and showed no signs of reproductive activity.

Remarks. Scott Block and Earl Zimmerman theorize that increasing warmer and drier periods in Texas climate beginning about 10,000 years ago may have led to the geographic isolation of this pocket gopher. As lengthy drought cycles caused accelerated soil erosion and a decrease in the former mesic vegetation of western Texas the increasingly xeric conditions may have served to help isolate G. texensis in the small range seen today, and contributed to its speciation.