Onychomys leucogaster (Wied-Neuwied, 1841) . Reise in Nord-America, 2:99.

TYPE LOCALITY: USA, North Dakota, Oliver Co., Mandan village near Fort Clark .

DISTRIBUTION: S Alberta, Saskatchewan, and SW Manitoba, Canada, south through Great Plains and Great Basin region of USA, to N Tamaulipas, Mexico.

SYNONYMS: albescens, arcticeps, breviauritus, brevicaudus, capitulatus, durranti, fuliginosus, fuscogriseus, longipes, melanophrys, missouriensis, pallescens, pallidus, ruidosae, utahensis.

COMMENTS: Geographic variation and subspecific taxonomy reviewed for central Great Plains (Engstrom and Choate, 1979) and for Great Basin region (Riddle and Choate, 1986). Biogeographic scenario of intraspecific differentiation developed by Riddle and Choate (1986). See McCarty (1978, Mammalian Species, 87).