The low representativeness of the dog‐faced bats (genus Cynomops Thomas, ) in collections has constrained the study of the diversity and the evolutionary relationships within this genus. Taxonomic revisions of some taxa, in particular the large‐sized Cynomops abrasus (Temminck, ), are crucial for understanding the phylogeny of Cynomops. A total of four subspecies of C. abrasus have been described to date, all widespread in South America: C. a. mastivus (Thomas, ), C. a. brachymeles (Peters, 1865), C. a. cerastes (Thomas, ) and C. a. abrasus (Temminck, ). Here, we evaluated the phylogenetic relationships within Cynomops, and the status of the four C. abrasus subspecies using complete sequences of two mitochondrial genes (Cyt b and COI) and 39 morphological characters. Maximum‐parsimony, maximum‐likelihood and Bayesian phylogenetic reconstructions recovered a novel hypothesis for Cynomops, supported the recognition of C. a. mastivus as a distinct species, separated from C. abrasus, and two hypotheses of lineages previously unrecognized for Cynomops. The use of mitochondrial genes combined with morphological characters revealed again to be a powerful tool to recover the phylogenetic relationships within Cynomops and demonstrated that the genus is more diverse than previously thought.