Una especie nueva de oxymycterus (Cricetidae: sigmodontinae: akodontini) del sureste de Perú

We describe a new species of the genus Oxymycterus from the high Andes of Cusco in southeastern Peru, based on information provided by the analysis of molecular data (cytochrome b), morphology and measurements. This species is notably different from all other Peruvian and Bolivian forms studied, specially O. nigrifrons and O. paramensis. It distinguishing traits include a comparatively medium body size, dorsal coloration brown yellowish with black hairs, no blackish supranasal patch, a long, anteriorly expanded incisor foramen with a developed septum occupying half to two-thirds of the foramen length, a quadrangular mesopterygoid fossa with hamular process of pterygoid near parallels, and the dorsal portion of the ectotympanic laterally expanded. Currently, the new species is only known from two small mountain ranges (Vilcanota and Vilcabamba) being isolated from other forms, that define it as an endemic species, highlighting the vulnerability risk associated with its restricted distribution.