Microtus ochrogaster (Wagner, 1842) . In Schreber, Die Säugethiere, Suppl. 3:592.

TYPE LOCALITY: USA, Indiana, Posey Co., New Harmony (as fixed by Bole and Moulthrop, 1942:157) .

DISTRIBUTION: Northern and Central Great Plains: EC Alberta to S Manitoba, Canada, south to N Oklahoma and Arkansas, eastwards to C Tennessee and westernmost West Virginia, USA; relictual populations in C Colorado, N New Mexico, and coastal prairies of SW Louisiana and adjacent Texas, USA.

SYNONYMS: austerus, cinnamonea, haydenii, ludovicianus, minor, ohioensis, similis, taylori .

COMMENTS: A member of Pedomys, a taxon used as a subgenus of Microtus (Bailey, 1900; van der Meulen, 1978), as a full synonym of Microtus (Hall, 1981), or as a synonym of Pitymys, whether the latter is used as a genus (Repenning, 1983) or subgenus (Hooper and Hart, 1962; Zagorodnyuk, 1990). The purported close affinity of M. ochrogaster with North American species of Pitymys has received little support from biochemical studies (Chaline and Graf, 1988; Moore and Janacek, 1990). Geographic variation over the Central Great Plains studied by Choate and Williams (1978). The strong morphometric segregation of minor from other M. ochrogaster advises renewed scrutiny of its status (Severinghaus, 1977). Includes ludovicianus, an isolated form of the coastal praires formerly consided a separate species and now apparently extinct (see Lowery, 1974). See Stalling (1990, Mammalian Species, 355).