The procyonid taxon Nasuella Hollister, 1915, is currently recognized as a monotypic genus comprising the single species N. olivacea (Gray, 1865), the Mountain Coati, found in montane habitats (circa 1300-4250 m) in the Andes of Venezuela, Colombia, and Ecuador. In this study we utilize museum specimens to examine the phylogenetic relationships, taxonomy and geographic distribution of Nasuella populations with an integrative systematic approach. Drawing on morphological comparisons of pelage, cranial, and dental characters, and molecular comparisons of the mitochondrial gene cytochrome b (from recent and historical samples), we confirm that Nasuella is closely related to other coatis (Nasua) and show that there are two deeply divergent lineages represented within the taxonomic bounds of Nasuella. We recognize and diagnose these taxa as two distinctive mountain coati species, corresponding to the Eastern Mountain Coati Nasuella meridensis (Thomas, 1901), endemic to the Venezuelan Andes, and the Western Mountain Coati N. olivacea, distributed in the Andes of Colombia and Ecuador. We use locality and habitat data associated with museum specimens to model the global geographic range of both species. From this we predict areas of undocumented (i.e., currently unvouchered) occurrence, areas of habitat loss associated with land use changes, and the geographic barrier separating the distributions of N. meridensis and N. olivacea. This newfound understanding of taxonomy and distribution should allow for a revised conservation assessment for mountain coatis.