Gnathia nubila n. sp. and a new record of Gnathia grandilaris (Crustacea, Isopoda, Gnathiidae) that parasitizes elasmobranchs from Okinawan coastal waters, Japan

Abstract

Gnathiid larvae were collected as ectoparasites on elasmobranchs caught in fisheries off Okinawa Island, Ryukyu Archipelago, southwestern Japan. The larvae were reared in a laboratory aquarium; some metamorphosed into male and female adults of Gnathia nubila n. sp. and Gnathia grandilaris Coetzee, Smit, Grutter & Davies, 2008. Males of G. nubila n. sp. were easily distinguished from all other species by the bifit and dentate mediofrontal process of the frontal border and by a narrow pleotelson. Gnathia grandilaris was originally recorded from the Great Barrier Reef (GBR), Australia, and here we report a second find of this species from the Ryukyus. Since the first description did not include female adult of G. grandilaris, we provide the morphology of female.