The dusky melanomys is a rodent of forests in western Colombia and southwestern Ecuador. Its back is generally dark, although coat color varies geographically. The 2017 species account says its broad taxonomic concept needs further revision.
The back varies geographically but is generally dark. Gray-based belly fur has pale buff tips, giving the underside a yellowish wash. The tail, ears, and feet are dark brown.
It is terrestrial and occurs in Andean and Pacific forests from sea level to about 2,300 m. In Chocó, Colombia, reproductive activity was recorded in March; one pregnant female gave birth to two young.
An extinction-risk assessment has not been added yet.