A new species of Alticola (Mammalia, Rodentia, Arvicolinae) from southern Tibet, China

The complex topography and diverse habitats of the Qinghai-Tibet Plateau have made it a center of speciation and evolution for various taxa, including small mammals. Our surveys in 2008 and 2023 on the southern part of the plateau discovered a population of mountain voles (genus Alticola ) not assignable to any known species. Specimens were collected from shrublands near streams (at elevations of 3,228–4,022 m) in Longzi and Lang counties, Tibet. Integrative taxonomic analyses, incorporating molecular phylogenetics and morphology, confirmed their distinct status. They form a well-supported clade that is sister to A. stoliczkanus , from which it diverged approximately 0.49 Mya (95% HPD interval: 0.20–0.77). Kimura-2-parameter distances for the complete cytochrome b gene between these individuals and other nominal species of Alticola range from 4.0% to 10.3%. Morphologically, this unique lineage is diagnosed by possessing the simplest M 3 with a truncated posterior lobe, a slender tail, darker pelage, and distinctive bacular characteristics. We describe this lineage as Alticola yarlungia sp. nov. This discovery suggests that species diversity within genus Alticola remains underestimated and underscores the need for continued biodiversity exploration in the eastern Himalayan region.