Species Diversity 25: 153–162 Published online 7 August 2020 DOI: 10.12782/specdiv.25.153 Elpidia soyoae, a New Species of Deep-sea Holothurian (Echinodermata) from the Japan Trench Area Akito Ogawa1,2,4, Takami Morita3 and Toshihiko Fujita1,2 1 Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan E-mail:
[email protected] 2 Department of Zoology, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan 3 National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan 4 Corresponding author (Received 23 October 2019; Accepted 28 May 2020) http://zoobank.org/00B865F7-1923-4F75-9075-14CB51A96782 A new species of holothurian, Elpidia soyoae sp. nov., is described from the Japan Trench area, at depths of 3570– 4145 m. It is distinguished from its congeners in having: four or five paired papillae and unpaired papillae present along entire dorsal radii (four to seven papillae on each radius), with wide separation between second and third paired papillae; maximum length of Elpidia-type ossicles in dorsal body wall exceeds 1000 µm; axis diameter of dorsal Elpidia-type ossicles less than 40 µm; tentacle Elpidia-type ossicles with arched axis and shortened, occasionally completely reduced arms and apophyses. Purple pigmentation spots composed of small purple particles on both dorsal and ventral body wall. This is the second species of Elpidia Théel, 1876 from Japanese abyssal depths. The diagnosis of the genus Elpidia is modified to distin- guish from all other elpidiid genera.