Nonetheless, individuals vary considerably in size, ranging from  in head-body length, with a relatively short tail  long. Body weight varies from ; no other sigmodontine species has a maximum weight above . The fur is thick and coarse, with an almost uniform shade of dark grey or brown across the whole of the body, although slightly paler on the throat and underside.
Individuals exhibit a wide range of sizes, from head-body length to tail length; body weight varies from ; no other sigmodontine species has a maximum weight exceeding . The fur is thick and coarse, with an almost uniform shade of dark grey or brown across the entire body, although slightly paler on the throat and underside.