Deep-sea Fauna and Pollutants off Pacifi c Coast of Northern Japan, edited by T. Fujita, National Museum of Nature and Science Monographs, No. 39, pp. 581-613, 2009 Thalassinidea, Anomura and Brachyura (Crustacea: Decapoda) from Northeastern Japan Collected during the “Research on Deep-sea Fauna and Pollutants off Pacifi c Coast of Northern Japan” Project Hironori Komatsu1 and Tomoyuki Komai2 1 Department of Zoology, National Museum of Nature and Science, 3̶23̶1 Hyakunincho, Shinjuku-ku, Tokyo, 169̶0073 Japan E-mail:
[email protected] 2 Natural History Museum and Institute, Chiba, 955̶2 Aoba-cho, Chuo-ku, Chiba, 260̶8682 Japan E-mail:
[email protected] Abstract: Reptantian decapod crustaceans (Thalassinidea, Anomura and Brachyura) from off the Pacifi c coast of northeastern Japan, collected during a four-year project of the National Museum of Nature and Science, “Research on Deep-sea Fauna and Pollutants off Pacifi c Coast of Northern Japan,” are reported. The collection consists of 26 species of 12 families. A new species of ethusid crab, Ethusina wakataka, is described and il- lustrated based on a male specimen from off Soma, Fukushima Prefecture, at depths of 1466̶1471 m. The new species can be distinguished from the known congeners primarily by the unique structure of the gonopods. The biogeography and the bathymetric distribution of the recorded species are briefl y discussed. Key words: Crustacea, Decapoda, Thalassinidea, Anomura, Brachyura, deep-sea, new species, Ethusina wakataka. Introduction Little has been published on the deep-water reptant decapods of the Pacifi c coast of northeast- ern Japan, although the area represents a major North Pacifi c fi shing ground.