This small harvest mouse is known from separated highland populations in Costa Rica and Nicaragua. Adults have a reddish back and a white-looking underside.
Adults have a rufous face and brighter reddish fur on the back, while the underside is clearer white. The short, smooth fur lies flat.
Mountain cloud forest is reported as a main habitat. A related group of R. mexicanus also occurs in similar habitat, but the study treats them as separate species.
An extinction-risk assessment has not been added yet.