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Species Diversity
Abstract
Three new sea cucumbers collected in the intertidal and subtidal zone of southern Japan, Taeniogyrus mijim sp. nov., Rowedota chippiru sp. nov., and R. motoshimaensis sp. nov., are described. All three species display a small body size (approximately 10–20 mm), light body colour (primarily a transparent solid colour), and a small number of digits in their tentacles (one pair or two). They are easily distinguished from each other and from other congeners by the number of digits and by ossicle size and shape. Among these species, the state of the tooth series on the inner margin of the wheel ossicles is an important defining feature, i.e., a continuous row in Taeniogyrus but interrupted by concavities in Rowedota. Also, each tooth is sharp in T. mijim, trapezoidal in R. chippiru, and semicircular in R. motoshimaensis. The number of teeth per radiant is 7–16 (means of 10–13 in different specimens) in T. mijim, 7–15 (means 9–12) in R. chippiru, and 8–21 (means 11–19) in R. motoshimaensis. Among these three new species, only R. chippiru has thick rod ossicles in the body wall.
We would like to thank Prof. Susumu Ohtsuka of the Takehara Marine Science Station of Hiroshima University for providing equipment for DNA analysis, and the entire staff of BIK and WMNH for invaluable assistance provided during this study. We also thank Dr P. Mark O'Loughlin and an anonymous reviewer for reviewing the manuscript; and Dr Keiichi Kakui and Dr Mark J. Grygier for careful editing. We are grateful to Mr Tohru Imaoka for his helpful advice. This work was partially supported by Research Institute of Marine Invertebrates (Tokyo) Grant 2015KO-1. Financial support for part of the microscopic observations was provided by Mr Shinichi Ikebe of the Supporters' Association of WMNH.
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