Taxonomic re-evaluation of New World Eptesicus and Histiotus (Chiroptera: Vespertilionidae), with the description of a new genus

. Eptesicus Rafinesque, 1820 is widely distributed in the Old and New World (26 species), and Histio-tus Gervais, 1856 is a South American endemic (11 species). Molecular phylogenies have recovered Eptesicus (sensu lato) as polyphyletic, with New World Eptesicus and the sister genus Histiotus in a paraphyletic American clade sister to Old World Eptesicus . Based on these phylogenetic reconstructions, authors have treated Histiotus as either a subgenus of Eptesicus or restricted Eptesicus to the New World species, treating Histiotus as a full genus, and using the name Cnephaeus Kaup, 1829 at the generic rank to comprise Old World Eptesicus . Based on recently published molecular studies, and on novel qualitative and quantitative morphological comparisons of representatives of Histiotus and New and Old World Eptesicus , we provide evidence for restricting the name Eptesicus to the species E. fuscus (Palisot de Beauvois, 1796) and E. guadeloupensis Genoways & Baker, 1975, allocating the remaining New World species under a new genus, keeping Histiotus as a full genus, and raising Cnephaeus to generic rank to comprise all Old World taxa currently under Eptesicus . This arrangement resolves the paraphyly of New World Eptesicus , and promotes taxonomic stability for Histiotus , which is a well-established genus of easily recognizable Neotropical bats and treated separate from Eptesicus by most authorities.