New Distribution Record of the Fish Parasitic Crustacean Cinusa nippon（Isopoda: Cymothoidae）, with a Description of the Manca

Cinusa nippon Nagasawa（Isopoda: Cymothoidae）, a marine parasite infesting the buccal cavities of coastal puffers, is newly recorded from the Pacific coasts of central Japan. A pair consisting of a mature female and mature male, and six mancae and a juvenile, were collected from reared vermiculated puffer, Takifugu snyderi（Abe）（Tetraodontiformes: Tetraodontidae）, in an aquarium and a museum, respectively. The present paper provides a description of the morphological characters of these cymothoids, including their immature stages, and molecular analysis using 16S rRNA for C. nippon and related species. In the maximum likelihood phylogenetic tree, C. nippon was included in the clade of Ceratothoa Dana and corresponds to Ceratothoa sp. 2 reported in another study. These suggest that the relationship between Cinusa Schioedte and Meinert and Ceratothoa needs to be re-examined. Furthermore, the morphological study showed that these cymothoid mancae are similar to Manca type 2 known from zoo-plankton, provided in one of our previous reports.