Redescription of the First Zoeal Stage of Shrimp Cinetorhynchus rigens (Gordon, 1936) (Decapoda: Rhynchocinetidae) and New Perspectives Including Scanning Electron Microscopy

ABSTRACT Cinetorhynchus occur mainly in shallow waters of temperate to tropical regions. Among the 28 species of Rhynchocinetidae, there are only six with larval morphology known and the description of the larva of Cinetorhynchus rigens is succinct. Thus, we redescribe the zoea I of C. rigens , add Scanning Electron Microscopy (SEM), and review the larval characters of the family. An ovigerous female was collected in the Fernando de Noronha archipelago (Brazil) and was maintained until eclosion of the zoeas I. The larvae were dissected, described and illustrated. The zoea I studied here has differences from the older description, which could indicate that they are distinct species. The first zoea of C. rigens can be distinguished from others of the genus by the posterior dorso‐median papillae, pterogostomian spine and number of aesthetascs, setae and spines in the maxillule and maxilla, setae and segments in the maxillipeds. The SEM revealed denticles on the endopods of the maxillipeds and on the surface of the setae on the telson. In addition, the SEM assisted in confirming characters that are hard to see under optical microscopy. Moreover, our study suggests that the SEM is an excellent additional tool that allows for more detailed larval descriptions.