A new species of vole (genus Microtus) from Oaxaca, Mexico. American Museum novitates ; no. 2243

Abstract

"The thickness of the base of the tail, which was lost during life, in the type of M. oaxacensis seems to indicate that the original tail was relatively long. Microtus oaxacensis has a long braincase and small bullae similar to those of M. umbrosus, but is distinct from M. umbrosus both externally and in the pattern of the triangles and folds on M³. In M. oaxacensis, M³ has five closed triangles; in M. umbrosus M³ has only two closed triangles. Microtus mexicanus fulviventer is smaller than M. oaxacensis and has a shorter and more angular skull, shorter and broader braincase, and larger bullae. Externally M. oaxacensis superficially resembles M. quasiater but differs in cranial and dental characters"--P. 4.