This rat is recorded from southern New Guinea. Historical specimens were described as having a brown tail mottled yellowish-white near the tip, and relatively narrow, pale-haired feet.
In his 1946 comparison, Troughton described R. ringens as having a longer tail than R. mordax; it was brown and usually mottled yellowish-white toward the tip. The feet were relatively narrow and pale-haired.
The original field book lists two females, specimens 14918 and 14919, collected at the same locality on 2 April 1936. The corresponding measurement rows record five large embryos in one and five small embryos in the other. Two animals from one date and locality do not establish a population-wide breeding season or rate.
An extinction-risk assessment has not been added yet.