Examination of its genome shows that this species is not closely related to Oxymycterus as had previously been thought, but is quite distinct, having diverged from the other Akodontini soon after the basal radiation of the entire group.

[3] The Andean rat is a medium-sized species, with a tail as long as or rather longer than its head-and-body length.

The head has a rather long but broadly-based snout and exposed, small, sparsely-haired ears.

The upper surfaces of the feet are grey, which contrasts with the white toes.

[2] The Andean rat is endemic to the eastern slopes of the Andes, its range including southern Peru and northern Bolivia.