ABSTRACT. Bats from southern Brazil: comparative analysis of species richness, new records and nomenclatural update (Mammalia, Chiroptera). A comparative analysis of the patterns of bat species richness in southern Brazil is presented, as well as similarity analyses among states. The highest richness of bat species is found in the state of Paraná, with 64 species, followed by Santa Catarina with 46, and Rio Grande do Sul, with 40. The family Phyllostomidae plays an important role in determining this pattern. The geographical distributions of Trachops cirrhosus (Spix, 1823), Artibeus cinereus (Gervais, 1851) and Thyroptera tricolor Spix, 1823 are expanded to the state of Paraná, establishing a new southern limit for these species and for Thyropteridae. In addition Myotis dinellii Thomas, 1901 is first recorded in Brazil, in Santa Catarina and Rio Grande do Sul, establishing a new eastern limit for this species. The distribution of Eptesicus taddeii Miranda, Bernardi & Passos, 2006 is extended by a new record in Rio Grande do Sul. An updated list of bats for the southern Brazilian states is presented with few nomenclatural adjustments. The importance of more intensive field efforts to survey the chiropterofauna is highlighted as a way to improve conservation efforts based on representative surveys and scientific collections.