A NEW ONISCOPSIS SPECIES (COPEPODA, HARPACTICOIDA) FOUND ON THE SANDY BEACH OF MUKAISHIMA ISLAND, THE INLAND SEA OF JAPAN

Abstract

In this paper, a new species of the genus Oniscopsis Chappuis, 1954 (Copepoda, Harpacticoida, Tetragonicipitidae: see Becker and Kunz, 1981) is described on the basis of some male and female specimens from the interstices of beach sand in Mukaishima Island, the Inland Sea of Japan. The genus Oniscopsis is, at present, composed of two species: 0. pauliani Chappuis, 1954 and 0. robinsoni Chappuis & Delamare Deboutteville, 1956. This is the first record of this genus from Japan. The sampling station is situated midway between M.H.W.S. and M.H.W.N. on the beach (about 3.1 meters above the datum line), where the mean grain size is approximately 1.8 mm in diameter. The material was obtained from sand samples by means of the so-called decanting-sieving method. Dissected somites and appendages were mounted on slides using Sasa's gum-chloral medium. Slide preparations used for the description are indicated by numbers in parentheses. The surface structure of the integument was examined with a scanning electron microscope, JSM-25 (Japanese Electron Optics Lab.). All specimens examined are deposited in the Mukaishima Marine Biological Station, Hiroshima University. Before going further, I would like to express my sincere thanks to Professor Akihiko Inaba of the Mukaishima Marine Biological Station, Hiroshima University, for his support and guidance to the present study. Sincere thanks are also due to Professor F.E. Round of the Department of Botany, University of Bristol, who read the manuscript with good grace. I am also grateful to Dr. Tatsunori Ito of the Seto Marine Biological Laboratory, Kyoto University, for giving beneficial advices.