O. pseudocardinale sp. n. (holotype 6: Brazil. Minas Gerais. Fazenda da Cachoeira F.F. de Souza. 13-11-1990) and O. sulmatogrossense sp. n. (holotype 6\ Brazil. Mato Grosso do Sul. Campo Grande. Campus UFMS, 24-XII-I997) are described and illustrated. The larvae of O. basale Selys, 1876; O. haematinum Selys, 1876; O. pavidum Selys, 1876: O. santosi Martins. 1967 and O. sulinum Costa. 1978 are described and illustrated for the first time. Keys are provided for the known Oxyagrion spp. and for the known larvae.