Thomomys nayarensis, a new species of pocket gopher from the Sierra del Nayar, Nayarit, Mexico

The southern pocket gopher, Thomomys umbrinus, traditionally has been divided into as many as 5 genetically defined subclades based on chromosomal and allozymic data. Recent molecular analyses have resurrected 2 species from within these clades: 1 from the Pacific coastal lowlands (T. atrovarius), and another from the highlands of the Sierra Madre Occidental (T. sheldoni). In this study, multilocus genetic analyses of 3 mitochondrial and 5 nuclear genes reveal a previously unrecognized 3rd species apparently restricted to the Sierra del Nayar of northeastern Nayarit, Mexico. In addition to molecular and chromosomal studies of this new species, cranial morphology is analyzed to help distinguish it from its congeners. This taxon, T. nayarensis, is described herein, and a key to distinguishing the 3 species of Thomomys in northeastern Nayarit is provided.