Review of South American Bats of the Genus Eptesicus

The systematics and nomenclature of South American bats of the genus Eptesicus are reviewed. Based upon the study of 317 specimens, seven distinct species are recognized, as follows: Eptesicus andinus, E. brasiliensis, E. dorianus, E. furinalis, E. fuscus, E. innoxius, and E. montosus. Of these species, E. andinus, E. furinalis, and E. fuscus occur also in Central America and Mexico. One new sub- species, Eptesicus brasiliensis thomasi, is described from the headwaters of the Amazon River. In a review of the genus Eptesicus, Tate (1942) commented that the greatest diversity of forms of this nearly cosmopolitan genus is found in Africa. According to him, Eptesicus is not well represented in South America, and those forms that do occur there appear on the whole to be unspecialized species derived from early Eptesicus stock. Even so, South America is much more richly endowed than North America with members of this genus. In addition to Eptesicus fuscus, the common big brown bat of North America, no fewer than six other species of relatively small Eptesicus are found there. Several of them superficially resemble bats of the genus Myotis, and only by examina- tion of the dentition can one readily separate the two genera. In Eptesicus the dental formula is i, 2/3; c, 1/1; pm, 1/2; m 3/3, but one cannot rely on dental formula alone to place specimens in the genus Eptesicus because another South American eptesicoid bat, His- tiotus, has the same formula. Histiotus, however, represents a branch of the eptesicoid stock characterized by greatly enlarged ears and audi- tory bullae; the width of the bullae is considerably more than their distance apart. I was able to assemble 317 specimens of Eptesicus from South Amer- ica for this review. These were mainly conventional study skins with skulls; the remainder were alcoholics from which the skulls were re- moved. These specimens are deposited in a number of institutional col- lections as follows: AMNH-American Museum of Natural History,