Nelson's spiny pocket mouse is known from cool, wet montane slopes. A comparison with another species describes its longer skull, larger ears, and soft dorsal fur.
Compared with Heteromys teleus, H. nelsoni is larger, with a more elongated skull and larger ears. The inner forearms are dusky, and the dorsal fur is soft.
The 2018 assessment reports it on cool, wet montane-forest slopes with epiphytes, moss, and fallen trees, and says its biology is poorly known.
An extinction-risk assessment has not been added yet.