A spiny rat known only from São Sebastião Island off southeastern Brazil. Its back bears reddish-brown spines, and much of the island is Atlantic rainforest.
The spiny dorsal fur is reddish brown streaked with black and darker along the mid-back. The underside is cream to light gray.
Broadleaf evergreen Atlantic rainforest is the dominant vegetation on São Sebastião Island. The study documents habitat and specimens but does not describe detailed behavior.
An extinction-risk assessment has not been added yet.