Genetic Identification of Pocket Gophers (genera Cratogeomys, Geomys, and Thomomys) in Texas and Surrounding Areas
Three genera of pocket gophers occur in Texas: Cratogeomys in the western third of the state, Thomomys in the montane regions of the Trans-Pecos Region and the southwestern portion of the Edwards Plateau, and Geomys statewide except for portions of the Trans-Pecos Region. However, due to considerable morphological conservation, differentiating among species and subspecies has been difficult, if not impossible. Advanced molecular markers such as DNA sequencing have proven useful in defining species boundaries and in generating phylogenetic relationships at the species level, but general taxon sampling and geographic representation has not been sufficient to provide a detailed assessment at the subspecific level. Herein, DNA sequence data obtained from the mitochondrial cytochrome-b gene was used to assess variation at the subspecific and species level for the three genera of pocket gophers occurring in Texas. Specimens collected from or adjacent to type localities were used to represent the genotype associated with each of the taxonomic names that have been proposed for Texas pocket gophers. Further, findings from previous morphometric, allozymic, karyotypic, and DNA studies were combined with DNA sequence data generated herein to assemble the broadest possible dataset for providing a taxonomic synthesis of each genus. In total, 22 taxonomic names were evaluated for Cratogeomys, 25 for Geomys, and 24 for Thomomys. For Cratogeomys occurring in Texas and immediate surrounding areas, 1 species and 13 subspecies were proposed; for Geomys occurring in Texas and immediate surrounding areas, 12 species and 18 subspecies were proposed; and for Thomomys occurring in Texas and immediate surrounding areas, 4 species and 22 subspecies were proposed. New distribution maps were provided to reflect the updated taxonomy. Forty-three original names were synonymized, elevated to species, or otherwise reassigned, and two new taxonomic entities were identified as needing official description.