The Least Big-eared Bat is a small bat known only from its type locality in western Amazonian Brazil. Only two specimens from the 1940s are known, and its diet is inferred from morphology.
It has a short tail and a blunt noseleaf. Two elongated pads occur on the chin, and its rounded ears are separate from each other.
Its Amazonian forest record is limited to the holotype and one other specimen. Based on teeth, skull, and comparison with a related species, it probably eats mostly arthropods and some fruit. Breeding and activity are unreported.
An extinction-risk assessment has not been added yet.