The holotype of Odontophrynus americanus collected by Alcide d'Orbigny in northern Patagonia, Argentina differs morphologically from the tetraploid frogs repeatedly assigned to this species and that are distributed from central Argentina and Uruguay to the north to Brazil and Paraguay (probably also Bolivia). Surprisingly, the external characteristics of the holotype match with the morphology of the adult syntype and specimens currently referred to as Odontophrynus occidentalis distributed in central, western, and southern Argentina. On the basis of resemblance in position, number, size, and shape of the glandular warts, we propose that O. americanus should be considered a senior synonym of O. occidentalis. Consequently, we realize that the tetraploid frogs currently called O. americanus were all too often misidentified under this name. After reviewing all the available names applicable to this tetraploid species, we recognize Hyperoodon asper described by Rodolfo A. Philippi as valid, resurrecting this nominal species within the genus Odontophrynus, with the designation of a neotype from Montevideo, Uruguay. We also propose that Ceratophrys argentina Philippi is a nomen dubium. To update the taxonomy of the genus Odontophrynus, we provide partial chresonymies, morphologic diagnoses, cytogenetic and bioacoustic characters, and geographic distribution maps for both O. americanus and O. asper.