Taxonomic position of Chinese voles of the tribe Arvicolini and the description of 2 new species from Xizang, China.

China has 26 species in the tribe Arvicolini. The taxonomic status of these voles remains controversial despite much effort. Herein, we evaluate the taxonomic position of 22 species plus 2 unidentified taxa using mitochondrial DNA gene sequences ( cytb + CO1 ). We also evaluate 18 species and 2 unidentified taxa using morphological data. Phylogenetic analyses of cytb resolve monophyly for the genera Alexandromys , Lasiopodomys , Microtus , Neodon , Proedromys , and Volemys with strong support. Stenocranius clusters with Chionomys but with very weak support. Analyses of concatenated cytb + CO1 resolve the same genera with strong support, but the topology of the tree differs from that of cytb in that Chionomys roots at the base of the tree independent of Stenocranius , which forms the sister-group of Lasiopodomys in a more terminal position. The matrilineal genealogy excludes the type species Arvicola amphibius from the rest of the Arvicolini. This species forms the sister-group of Ondatra with high support. Neodon includes N. irene , N. linzhiensis , N. fuscus , N. leucurus , N. sikimensis , Microtus clarkei , and 2 unidentified specimens. Alexandromys includes the former species Microtus oeconomus , M. kikuchii , M. limnophilus , M. fortis , and M. maximowiczii . Finally, Microtus has the subgenera Blanfordimys , Microtu s, Mynomes , Pedomys , Pitymys , and Terricola , which includes the Chinese species M. agrestis , M. arvalis , and Blanfordimys juldaschi . General mixed Yule-coalescent species delimitation modeling demarcates 6 currently recognized species and 2 new species of Neodon . A principal component analysis of the morphological data among 7 matrilines shows that all variables have positive loadings of high magnitude on the 1st component. Canonical discriminant analysis for Neodon (including M. clarkei and 2 unidentified species) correctly classifies 93.0% of specimens. Overall, our analyses support the recognition of Alexandromys , Lasiopodomys , Microtus , Neodon , Proedromys , and Volemys as genera. Stenocranius includes Microtus gregalis , and the genealogical position of Stenocranius remains uncertain. The status of Arvicola requires further study. We assign M. clarkei to Neodon and describe 2 new species of Neodon .