Microtus fortis Büchner, 1889 . Wiss. Res. Przewalski's Cent.- Asien. Reisen, Zool., I:(Säugeth.), p. 99.

TYPE LOCALITY: China, Nei Mongol, Ordos Desert, Huang Ho Valley, Sujan .

DISTRIBUTION: Transbaikalia and Amur region south through Nei Mongol and E China to lower Yangtse Valley and Fujian (see Kovalskaya et al., 1988).

SYNONYMS: calamarum, dolichocephalus, fujianensis, michnoi, pelliceus, uliginosus.

COMMENTS: Subgenus Alexandromys . Geographic variation in chromosomal traits and its significance was reported by Kovalskaya et al. (1988; 1991). Most researchers view this species as a close phylogenetic relative of M. mongolicus (Meier, 1983; Radjabli et al., 1984). Zagorodnyuk (1990) listed M. fortis as the only member of its species group and related to the M. middendorffi group, which contains M. middendorffi, M. miurus, M. mongolicus, and M. sachalinensis . Reviewed by Corbet (1978c) and Gromov and Polyakov (1977).