The taxonomy of the giant ants of the genus Dinoponera is revised based on female and male morphology. Eight species are recognized. Dinoponera nicinha sp. nov., from Amazonas and Rondônia, Brazil, is described and D. grandis (Guérin-Méneville, 1838) is revived. The species D. australis Emery, 1901 and D. snellingi Lenhart, Dash & Mackay, 2013, plus the subspecies D. australis bucki Borgmeier, 1937 and D. australis nigricolor Borgmeier, 1937 are synonymized under D. grandis sp. rev. An unnamed and unidentified male is reported. In general, male morphology has greater and more discrete variation than in females, but they are scarce in museum collections. Species distributions are updated and illustrated, the genus ranging from southern Colombia to northern Argentina, with no reliable records from the Guiana Shield and all nominal species occurring in Brazil. Intraspecific variation and natural history are discussed. New illustrated identification keys are provided for both sexes. Future studies should address the collection of fresh specimens for molecular work and to assess the conservation status of several species and populations.