Gauromydas Wilcox, Papavero & Pimentel, 1989 are giant flies, and include the largest fly known, G. heros (Perty, 1833). This genus was originally erected to group four Neotropical species, namely G. apicalis (Wiedemann, 1830), G. autuorii (d'Andretta, 1951), G. heros, and G. mystaceus (Wiedemann, 1830). As with most of the remaining Mydidae, adults of Gauromydas are very rarely collected. We here describe two new species of Gauromydas (G. mateus sp. nov. and G. papaveroi sp. nov.) discovered in entomological collections, including specimens unstudied for up to eight decades. We also provide revised diagnoses for the remaining four species of Gauromydas, along with a new key and new distribution records for the genus.