A revision of East Asian Acanthomysis (Crustacea: Mysida: Mysidae) and redefinition of Orientomysis, with description of a new species

Abstract

Twenty species of Acanthomysis s. l., distributed in Japanese, Korean and Chinese coastal waters, are revised. These species are distinguished from Acanthomysis s. str. by the following characters: the carpopropodus of the endopod of the third to eighth thoracic limbs divided into three to eight subsegments; the exopod of the fourth male pleopod with two long subequal terminal setae; the telson long linguiform or triangular without basal dilated portion and armed with spines throughout margins. On the basis of these characters, the genus Orientomysis, which was revived by Holmquist (1981b) and comprised O. japonica and O. mitsukurii, is redefined and recognized to contain the following 18 valid species: O. aokii, O. aspera, O. crassispinosa, O. fujinagai, O. hwanhaiensis, O. koreana, O. leptura, O. meridionalis, O. okayamaensis, O. pseudomitsukurii, O. robusta, O. rotundicauda, O. sagamiensis, O. serrata, O. sheni, O. tamurai, O. tenella, and O. tenuicauda. Acanthomysis longicauda and A. nakazatoi are synonymized with O. rotundicauda and O. japonica, respectively. A new species, O. arenaria, is described from Japan.

Keywords:

• Acanthomysis
• Crustacea
• East Asia
• Mysida
• Orientomysis
• taxonomy

Acknowledgments

The authors extend sincere gratitude to Drs R. Liu, S. Wang (Institute of Oceanology, Chinese Academy of Sciences), S.‐G. Jo (Kunsan National University, Korea), Y. Hanamura (National Research Institute of Fisheries and Environment of Inland Sea, Japan), K. Kimoto and H. Yamada (Seikai National Fisheries Research Institute, Japan) for providing specimens. We also thank Prof. T. Ishimaru and the members of Plankton Laboratory, the captain and crew of TR/V Seiyo‐Maru (Tokyo University of Fisheries), and the captain and crew of R/V Tansei‐Maru (Ocean Research Institute, University of Tokyo) for cooperation during collection of materials. We also thank Dr W. Price (University of Tampa) for reading the manuscript.