RESUMO: Species of the genus Brachysiderus Waterhouse, 1881 (Dynastinae), are revised, redescribed, and illustrated based on males and females, when available. A new species, Brachysiderus andinus sp. nov., previously treated in the collections and in the literature as Brachysiderus quadrimaculatus Waterhouse, 1881, is described from the Peruvian Andes. Brachysiderus tridentiger (Prell, 1934) stat. rev. and Brachysiderus breyeri (Martínez, 1963) stat. rev. are reinstated at the species level. Identification keys for males and females are provided, along with a new distribution map including new records from Bolivia and Brazil.