The neotropical genus Notodiaptomus Kiefer, 1936 (Calanoida : Diaptomidae): Redescription of the type species Notodiaptomus deitersi (Poppe, 1891) and designation of a neotype

Notodiaptomus Kiefer, 1936 is the most abundant and speciose genus of fresh water calanoids in the Neotropical region. The type species, N. deitersi (P oppe, 1891) is in need of redescription but the type material is no longer extant and the type locality no longer exists. In order to avoid possible c onfusion over the identity of the type species of the genus, a neotype is d esignated. This is an adult male from Baia Pedra Branca because this locali ty is near Cuiaba, in the State of Mate Grosso, Brazil, the original type l ocality. The neotype is described and this description forms the basis for a complete diagnosis of the genus Notodiaptomus. Like most diaptomid genera Notodiaptomus is characterized by prosome morphology, by the fifth legs in both sexes and by the male geniculate antennule. Sexual dimorphism in the rostrum is reported here and the homology of the modified setal elements on the geniculate right antennule of the male is analysed.