methodsFor the morphological study, individuals of 20 species in repro-ductive phase were collected in Brazil, in the states of Bahia, Ceará,Goiás, Mato Grosso and São Paulo, in rivers and temporary ponds during the rainy season (Table 1). Part of the material was made into herbarium specimens and deposited at the HUEFS herbariumand part was fixed in FAA50(Johansen, 1940) and stored in 70%alcohol for anatomical study.