Oligoryzomys microtis (Allen, 1916) . Bull. Am. Mus. Nat. Hist., 35:525.

TYPE LOCALITY: Brazil, Amazonas, lower Rio Solimôes .

DISTRIBUTION: C Brazil south of Rios Solimöes-Amazon, and contiguous lowlands of Peru, Bolivia, Paraguay, and Argentina.

SYNONYMS: chaparensis, fornesi, mattogrossae .

COMMENTS: Karyotype reported by Gardner and Patton (1976) as Oryzomys longicaudatus variant (2) and by Myers and Carleton (1981) as Oryzomys fornesi .