ABSTRACT Eptesicus Rafinesque, 1820 is widely distributed in the Old and New World (26 species), and Histiotus 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.

ABSTRACT Reserva Ecológica de Guapiaçu (REGUA) is a private, protected area inside a remnant of the Atlantic Forest with high biodiversity. Although the bats of the reserve have been sampled for more than two decades, few studies have been published about them. Based on a compilation of data from several surveys, we present an updated list of the bat species there and compare it with surveys from other locations in the Atlantic Forest. From August 1998 to September 2021, at least 194 sampling nights were carried out at REGUA by different research groups from various institutions, totaling 448,092 m2.h of sampling. A total of 4,069 individuals were captured, belonging to 47 species and six families. Additionally, our results indicate that it is possible that some species that occur at REGUA have not been recorded yet. REGUA has the greatest number of bat species known for the Atlantic Forest. This most likely results from the fact that the reserve includes large areas of mature, continuous forest connected with other protected areas in the State of Rio de Janeiro. Another factor contributing to the high diversity of bat species at REGUA is that the area has been intensely sampled for many years. Given that the bat assemblage there appears to be a good proxy to ascertain the ecological patterns of biodiversity in well-preserved forests, we consider REGUA to be an important area for long-term ecological research. The basic knowledge about the ecological interactions of bats with different food resources and zoonotic microorganisms offers a unique opportunity to carry out research in several areas of knowledge, making it possible to address questions about bat assemblage structure, bat-parasite ecology, competition, niche partitioning, and other related studies.