Yunnan field mouse Apodemus ilex O. Thomas, 1922 (Rodentia, Muridae); a new species and genus for the Vietnamese fauna, first recorded from Son La Province

During fieldwork conducted in the Bac Yen District of Son La Province, near the Ta Xua Nature Reserve, a representative of a previously never registered genus and species of rodent in Vietnam, the Yunnan field mouse (A. ilex O. Thomas, 1922), was discovered.This finding significantly expands our knowledge of the distribution of Apodemus species in northeastern Indochina. Morphological and genetic analysis of the specimen ruled out accidental introduction and established that the Vietnamese population is natural and belongs to the eastern phylogenetic branch of this species, which also inhabits the southern Yunnan-Guizhou Plateau, as well as the upper reaches of the Mekong, Hong Ha, and Da Rivers.

Thus, the list of rodent species and genera in Vietnam has been expanded with a new species. Data on the species' geographic distribution across its range are also provided.