Neocyclops Gurney from Brazilian sandy beaches (Copepoda: Cyclopoida)

Neocyclops medius Herbst, 1955 and Neocyclops vicinus (Herbst, 1955) are redescribed from intertidal interstitial water of sandy beaches along the Brazilian coast. The male of N. vicinus is described for the first time. Neocyclops vicinus can be easily distinguished from N. medius by the relatively longer caudal rami, the presence of a mandibular palp, and the sexually dimorphic antenna. This study revealed the leg 4 endopodite segments 2 and 3 as being fused in both species. The terminal segment of the 2-segmented leg 4 endopodite of the copepodite 5 does not differentiate into 2 distinct segments during the molt to adult. The plane of fusion is marked by a thin and incomplete line on the frontal surface. This scar was erroneously interpreted as a functional articulation by Herbst (1955). Topotypes of N. salinarum (Gurney, 1927) examined showed a similar fusion of those segments of leg 4. Populations from the Black Sea coast ascribed to N. vicinus differ from the Brazilian specimens in a number of morphological details, sufficient to propose that they represent a separate taxon, perhaps N. remanei (Herbst, 1952). A diagnosis for Neocyclops is provided.