As currently understood, the genus Nyctinomops contains four species: N. aurispinosus (Peale, 1849), N. femorosaccus (Merriam, 1889), N. laticaudatus (É. Geoffroy St.-Hilaire, 1805), and N. macrotis (Gray, 1840). Only N. macrotis and N. laticaudatus have been recorded from Argentina. We found that specimens of
Nyctinomops captured in the province of Misiones, Argentina did not correspond to the characters of either species known from Argentina, and did not match characters of any other known species. Morphological, morphometric, and molecular analyses of these specimens revealed that they represent a new species, which we describe herein.