Mastomys pernanus (Kershaw, 1921) . Ann. Mag. Nat. Hist., ser. 9, 8:568.

TYPE LOCALITY: SW Kenya, Amala (Mara) River; see Allen (1939:406) and Misonne and Verschuren (1964:655) for details .

DISTRIBUTION: Published records are from SW Kenya, NW Tanzania, and Rwanda (Misonne and Verschuren, 1964); limits are unknown.

COMMENTS: Ellerman (1941) listed pernanus as a distinctive species of Rattus in the subgenus Mastomys, but earlier Allen (1939) had treated it as a species of Myomys . Robbins and Van der Straeten (1989) claimed this a possibility. Misonne and Verschuren (1964, 1966b), however, discussed the problem and concluded that pernanus should be associated with Mastomys . Either postulated generic association is unsupported by critical analyses of comparative data so the allocation of pernanus remains clouded. The species is known by very few specimens (Misonne and Verschuren, 1964; 114439 in the American Museum of Natural History is from NW Tanzania).