A 2013 study re-recognized the former subspecies M. nigricans caucensis as a full species. The appearance account is based on seven Colombian specimens, while the broad range and habitat draw on records under the former subspecies name.
Specimens from Valle del Cauca had nearly uniform dark-brown backs. The underside was slightly paler, with black hair bases and pale ochre-buff tips.
The review assigns to this species records formerly grouped as M. nigricans caucensis, from lowland and mountain-slope forests up to high-elevation scrub-steppe. Those earlier records span about 200–2,600 m.
An extinction-risk assessment has not been added yet.