Proechimys oris Thomas, 1904 . Ann. Mag. Nat. Hist., ser. 7, 14:105.

TYPE LOCALITY: Brazil, Parâ, Igarapé-assû, near Belem .

DISTRIBUTION: C Brazil.

COMMENTS: Subgenus Proechimys . Formerly included in cayennensis (= guyannensis); see Reig et al. (1980). The chromosome no. is 2n=30.