Distributional information is presented for thirty-eight species of Gerromorpha and five Nepomorpha, including first records from the Brazilian states of Bahia (Mesovelia amoena), Ceará (Limnogonus profugus and Rhagovelia whitei), Espírito Santo (R. lucida), Goiás (Halobatopsis platensis and R. zela), Mato Grosso (Rheumatobates bonariensis), Pará (Nerthra terrestris), Paraná (H. spiniventris, Hydrometra fruhstorferi and R. janeira), Piauí (Microvelia ayacuchana, M. pulchella, Neogerris lubricus and Platyvelia brachialis), Rio de Janeiro (Martarega bentoi) and São Paulo (Rheumatobates minutus flavidus); and the Peruvian region of Madre de Dios (Rhagovelia fontanalis).