This small rice rat occurs in northern South America. In the Venezuelan Llanos, it was frequently captured in grassland and lowland savanna.
The fur is yellowish brown above, with stronger rufous brown along the middle of the back. The underside is buff, and the upper surfaces of the feet are yellowish white.
In the Venezuelan Llanos, the species was among the most frequently captured rodents in Paspalum savanna and lowland savanna. The field records were published under O. fulvescens; the 2015 chapter includes that northern South American group in O. delicatus.
An extinction-risk assessment has not been added yet.