Dicrostonyx richardsoni Merriam, 1900. Proc. Wash. Acad. Sci., 2: 26.

TYPE LOCALITY: Canada, Manitoba, Fort Churchill.

DISTRIBUTION: Canada west of Hudson Bay.

COMMENT: The extent of westward distribution is unknown. The diploid number is 44 for males and 42 for females and the fundamental number is 50; formerly included in torquatus; see Rausch, 1977, in Sokolov, ed., [Adv. Mod. Theriol.], Acad. Sci. U.S. S.R., Nauka, Moscow, pp. 162- 177; or groenlandicus; see Hall, 1981:836.