On the nauplius ofCentropages yamadai Mori, copepoda

Abstract

The nauplius ofC. yamadai shows the shape of typicalCentropages nauplius, as inC. hamatus andC. abdominalis. The nauplii of genusCentropages are oval in shape; somewhat rounded anteriorly and slightly pointed posteriorly. The rostrum is comparatively large. A nauplius eye is large at the proximal portion of the rostrum. There is a labrum with the minute spines on its posterior border. The antennule of 3 segments is oar-liked in outline as inCalanus, but on the ventral margin of terminal segment there is no seta. The abdominal portion is not divided from the carapace like that ofTemora orCalanus. There is no dorso-ventral flexure. The furcal setae are thick and long, and asymmetrical. An end seta which presents just dorsally against to a median seta, elongates backwards. The nauplius ofC. yamadai can be distinguished from nauplii of other species by the structure of appendages in the respective stages, but this nauplius is easily identified by the coloured body.