Apeco Thomasomys is a large rodent known from a limited area of north-central Peru. It has long, dense dorsal fur and records from upper montane forest and wet open habitat near forest edges.
The dorsal fur is long and dense. Its color varies among specimens from raw sienna through ochraceous tawny to tawny olive, streaked with black guard hairs. The underside is ochraceous buff, with variable extent.
It inhabits upper montane forest and jalca, a páramo-like open habitat, near forest borders. Capture records include a log end, a stream bank, forest floor, and wet pampa.
An extinction-risk assessment has not been added yet.