The lacked‐teeth pygmy weasel, Mustela aistoodonnivalis Wu & Kao, 1991, was originally described as being from Taibai Mountain and Zhashui county, Shaanxi, China. Subsequently, it was considered a subspecies or synonym of Mustela nivalis. In a faunal survey of northwestern Sichuan, eight specimens of M. aistoodonnivalis were collected. A molecular phylogenetic analysis of one mitochondrial and six nuclear genes clustered the specimens as a distinct clade and not with M. nivalis. Morphologically, the lack of the second lower molar differentiated them from M. nivalis, and genetic distances were typical of discrete species. These analyses confirmed that M. aistoodonnivalis is an independent species in the genus Mustela.

Shrews in the genus Episoriculus are among the least known mammals in China. It occurs mainly in the Himalayas and the Hengduan Mountains. We report the sequencing and analyses of one mitochondrial gene (Cytb) and three nuclear genes (Apob, Brca1, and Rag2) for 77 specimens, and analyses of morphological measurements for 56 specimens. Phylogenetic and morphological studies answer three longstanding questions. First, Episoriculus sacratus and E. umbrinus are valid species, and not subspecies of E. caudatus. Second, Pseudosoriculus fumidus is a valid taxon that does not belong to the genus Episoriculus. Third, the genus Episoriculus has eight valid species: E. baileyi, E. caudatus, E. leucops, E. macrurus, E. sacratus, E. soluensis, Episoriculus sp., and E. umbrinus. Ultimately, we erected subgenus Longacauda subgen. nov. for morphologically distinct E. macrurus, which leaves the nominate subgenus Episoriculus with the remaining seven congeners.