[2] It is found in a variety of habitats, including dense forest, in Bolivia and Peru at elevations from 450 to 2,100 metres (1,480 to 6,890 ft) on the eastern side of the Andes.

It is distinguished from the Brazilian arboreal mouse (R. rufescens), the only other known member of Rhagomys, by spiny fur and certain skull features such as the presence of beading in the interorbital region.

The fur is short and dense, and consists of a mixture of long slender hairs and spines, giving the mouse a bristly appearance.

The hind feet are short and broad and have five digits with blunt, calloused tips, the hallux (big toe) being shorter than the others and having a nail rather than a claw.

Examination of the stomach contents showed that the diet includes flies, ants and moths, and the short gut and crested teeth reinforce this hypothesis.