Taxonomic Note on Nannastacus nyctagineus (Crustacea: Cumacea: Nannastacidae) from Korean Waters

Korean nannastacids have recorded only eight species belonging to genera Campylaspis and Cumella. In this paper, Nannastacus nyctagineus Gamȏ, 1962, is redescribed and illustrated as a new species of Korean fauna in this study for the first time. Korean female specimens of Nannastacus nyctagineus correspond well with the original description by Gamȏ, 1962 based on only female specimens. Gamȏ has described that new species, Nannastacus pruinosus could be distinguished from N. nyctagineus based on only male specimens. The Korean male specimens of N. nyctagineus undoubtedly match well with the description of N. pruinosus with the following common features: the surface of the carapace is covered with numerous granules; pereonites and pleonites have similar patterns of the teeth on dorsal surface; the proportion and armature of the dactylus of pereopod 2 is similar; the number and pattern arrangement of the setae on the surface in antenna 1, pereopod 1, and uropod are the all most same. Nannastacus pruinosus Gamȏ, 1962 is proposed as a synonym of N. nyctagineus described in this study. This represents the first record on the genus Nannastacus from Korea.