Holocanthon is a dung beetle genus distributed across South American open environments such as the Humid Chaco, the Brazilian Cerrado and the Argentinian Espinal, as well as some more forested localities in the southern Atlantic Forest and in the Bolivian and Argentinian Yungas. Considered monospecific for more than 60 years, the genus now includes two species: H. fuscorubrus (Blanchard, 1846), new comb. (= H. mateui Martínez et Pereira, 1956, new junior subjective synonym), from Paraguay, Argentina and southern Brazil, and H. giosilvai Sawaris, Cupello & Vaz-de-Mello sp. nov., known only from three distant localities in Bolivia and southern Brazil. The lectotype of Canthon fuscorubrus is herein designated from the only known syntype, while the holotype and the rest of the type series of H. mateui is deemed to be lost.