Proechimys longicaudatus (Rengger, 1830) . Naturgesch. Säugeth. Paraguay, p. 236.

TYPE LOCALITY: N Paraguay .

DISTRIBUTION: C and E Peru, W Bolivia, Paraguay, S Brazil.

SYNONYMS: boimensis, elassopus, leucomystax, pachita, roberti, securus.

COMMENTS: Subgenus Proechimys . Formerly included brevicauda (Reig et al., 1980) . The chromosome no. is 2n=28.