A Note on the Genetic Status of the Dark Red-Backed Vole, Myodes rex, in Hokkaido, Japan

The dark red-backed vole, Myodes (formerly Clethrionomys) rex, was first described from specimens collected on Rishiri Island, Hokkaido, northernmost Japan, by Imaizumi (1971) as a new species on the basis of the cranial characteristics, which differ from those of the gray red-backed vole, M rufocanus, in the Hokkaido area (including Hokkaido and the peripheral islands), Japan. Myodes rex is thought to be rarer than the other Myodes voles, M rufocanus and M. rutilus, as shown by the collection of records of M. rex, which is quite limited, according to Nakata (2000). In addition, M rex is ranked as NT (Near Threatened) by the Ministry of the Environment of Japan (Ohdachi et al. 2009). Kaneko and Sato (1993) and Nakata (1995, 2000) reported that M. rex prefers grass fields, abandoned cultivated lands near grass fields, valley bottoms, and higher altitude forests as its habitat. In contrast, M. rufocanus prefers a habitat of Sasa dwarf bamboo, which is extensively distributed throughout Hokkaido (Toyooka et al. 1983).