Two new species of Protonephrocerus Collin, P. flavipilus Skevington, Marques & Rafael sp. nov. and P. misionensis Skevington sp. nov. are described. The only other currently recognized species in the genus, P. chiloensis Collin, is redescribed and genetic data ascribed to this species are transferred to P. flavipilus sp. nov. All previously published genetic data refer to P. flavipilus sp. nov. The first records of Protonephrocerus in Argentina are documented.