Biogeography 22. 53–57. Sep. 20, 2020 New distributional records of three species of sea stars (Echinodermata, Asteroidea) from the coast of the Kii Peninsula, Japan Hisanori Kohtsuka 1*, Hiroki Yamauchi 2, Tetsuya Kato 2 and Yoichi Kogure 3 1 Misaki Marine Biological Station, The University of Tokyo, 1024 Koajiro, Misaki, Miura, Kanagawa 851-0121, Japan 2 Field Science Education and Research Center, Seto Marine Biological Laboratory, Kyoto University, 459 Shirahama, Nishimuro, Wakayama 649–2211, Japan 3 Japan Sea National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 1-5939-22 Suido, Chuo, Niigata, Niigata 951-8121, Japan Abstract: Three sea star species belonging to three families were sampled from the coast of Wakayama Prefecture of the Kii Peninsula, southern Japan. All of these species, ophidiasterid sea star Ophidiaster multispinus, oreasterid sea star Halityle regularis and asteriid sea star Coronaster sakuranus are the first records from Wakayama Prefecture. Among them,H. regularis is a tropical/subtropical species rarely encountered in Japanese waters. The small body size of H. regularis captured may indicate the abortive migration of this sea star. Key words: Ophidiaster multispinus, Halityle regularis, Coronaster sakuranus, new distributional record, Wakayama Prefecture. Introduction dius, the distance from the center of the disc to the edge where two arms meet; R/r, the ratio of arm length to disc radius. Sea star (Asteroidea) is one of the dominant groups of echinoderms including nearly 1900 extant species from the Ophidiasteridae world’s oceans, ranging from tropical to polar latitudes, from Ophidiaster multispinus Liao & A. M. Clark, 1996 intertidal to abyssal depths (Mah & Blake, 2012). To date, 254 Japanese name: Mitsutoge-houkiboshi valid species in 29 families are known from Japan (Kogure, (Fig. 1A-D) 2018); however, the Japanese sea star fauna is still not fully uncovered (Saba et al., 2002). It can be proved by the fact Ophidiaster multispinus Liao & A. M. Clark, 1996: 37–39; that more and more undescribed species and the first recorded Lane et al., 2000: 473; Clark & Mah, 2001: 339; Kogure et species have been discovered in Japanese waters since 2000s al., 2012: 134–137. (Kogure & Fujita, 2012; Kogure & Igei, 2013; Kogure & Material examined. One specimen; OMNH-Iv 8433; R = 100 Kaneko, 2018; Kogure & Kohtsuka, 2012). mm, r = 10 mm, R/r = 10; Sakai Fishing Port, Minabe-cho, In recent years, a number of previously unrecorded tropical/ Hidaka-gun, Wakayama Prefecture, Japan; gill net; collected subtropical echinoderms other than asteroidea have been re- by Sadao Inoue on March 30, 2017 (preserved in ethanol on ported in succession from the southwestern waters of the Kii October 9, 2019). Peninsula (Wakabayashi et al., 2010; Kohtsuka & Kato, 2012; Description. Disk small; 5, relatively long arms (R/r = 9.6). Kohtsuka et al., 2018). In this paper, we describe the localities Abactinal and marginal plates arranged in 7 regular longitu- and external features of three species of sea stars collected for dinal series: 3 series of abactinal plates between both supero- the first time from Wakayama Prefecture of the Kii peninsula marginal plates. Actinal surface densely covered with round in order to add the information about the echinoderm fauna in polygonal granules. Superomarginal and inferomarginal plates the waters around this peninsula. bearing various numbers of short spines. Furrow spines com- The specimens examined in this study have been deposited posed of long, truncated spines, 2 on each adambulacral plates in the Osaka Museum of Natural History (OMNH). The fol- (Fig. 1C). One of furrow spines much larger than other spine; lowing abbreviations are used herein: R, arm length, as meas- thus, continuous furrow series consisted of large and small ured from the center of the disc to the tip of the arm; r, disc ra- spines alternating along furrow. Papular areas distinct, large, −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− sunken, covered with small granules, forming 8 longitudinal *Corresponding author: [email protected] series. Numerous papulae in one papular area, up to 30. Abac- – 53 – Three sea stars from the coast of the Kii Peninsula Fig. 1. Three species of sea stars (Echinodermata, Asteroidea) from the Kii Peninsula coast. Ophidiaster multispinus (OMNH-Iv 8433), A: abactinal view, B: actinal view, C: adambulacral armature at proximal part of arm (Red dots indicate furrow spines, green dots indicate supplemental subambulacral spines, and blue dots indicate subambulacral spines), D: abactinal pedicellaria (arrows indicating pedicellaria). Halityle regularis (OMNH-Iv 8434), E: abactinal view, F: abactinal pap- ular area, G: actinal view, H: proximal odd plate and coarse granules surrounding the plate, I: adambulacral armature (white arrows indicating the lanceolate pedicellariae). Coronaster sakuranus, J: abactinal view, K: actinal view, L: cruciform principal plates, M: furrow and subambulacral spine (Red dots indicate frrow spines, blue dots indicates subambulacral spines). J-K (OMNH-Iv 8436), L-M (OMNH-Iv 8435). – 54 – Hisanori Kohtsuka, Hiroki Yamauchi, Tetsuya, Kato and Yoichi Kogure tinal plates with two claw-like pedicellariae (Fig. 1D). Single actinal plates around the mouth are brightly vivid purple. The large madreporite, rounded triangle in shape, engraved with coloration of adambulacral plates, mouth plates, tube feet is fine striations, located near margin of disk. light pale yellow. Color in life. The abactinal surface is brownish, mottled with Distribution. Type locality: the Sulu Archipelago in the large patches of dark brown. All the papular areas are dark southwestern Philippines at depth of 16 m. Other localities: brown. The actinal surface is yellowish white. tropical/subtropical Indo-West Pacific regions including New Distribution. Type locality: the Hainan Strait, southernmost Caledonia (Jangoux, 1986), the Philippines, Western Australia, China at depth of 55 m. Other localities: Amoy of Fujian Somalia, Madagascar, Kenya (Baker & Marsh, 1976). Province and Hong Kong Island in southern China (Liao & Occurrence in Japanese waters: Kumejima Island of Okinawa Clark, 1996); Nagasaki Prefecture, the Oki Islands of Shimane Prefecture (Kogure & Fujita, 2012), Kochi Prefecture Prefecture (Kogure et al., 2012), and Minabe of Wakayama (Nakachi, personarl message), and Minabe of Wakayama Prefecture (present study) in Japan. Prefecture (present study). Remarks. The external features of this specimen such as the Remarks. The external features of this specimen such as small disk with long slender arms (R/r = 10), pairs of larger large disk with short arms having wide base and clearly and smaller furrow spines lacking associated granules, a row distinguishable actinal plates agree with the description of of supplemental subambulacral spines at proximal part of Kogure & Fujita (2012). However, the number of the actinal arms, and single bare madreporite are consistent with the pre- plates near the mouth, the furrow spines, and the pedicellariae vious reports of Liao & A. M. Clark (1996) and Kogure et al. on the adambulacral plates is less than the number of those (2012). reported by Kogure & Fujita (2012). These differences are attributed to the smaller body size of the examined specimen. Oreasteridae In the study area, no larger specimens have been discovered; Halityle regularis Fisher, 1913 thus, the present findings may indicate the abortive migration Japanese name: Ruriiromozaiku-hitode of this tropical sea star. (Fig. 1E-I) Asteriidae Halityle regularis Fisher, 1913: 211; 1919: 362; Döderlein, Coronaster sakuranus (Döderlein, 1902) 1935: 108, A. M. Clark & Rowe, 1971: 53; Baker & Marsh, Japanese name: Sakurakanmuri-hitode 1976: 107; Jangoux, 1986: 124; A. M. Clark, 1993: 304; Rowe (Fig. 1J-M) & Gates, 1995: 102; Kogure & Fujita, 2012: 252. Culcitaster anamesus H. L. Clark, 1914: 144. Asterias volsellata var. sakuranus Döderlein, 1902: 332. Halityle anamesus: H. L. Clark, 1946: 109. Coronaster sakuranus Hayashi, 1943: 188; 1973: 98; Imao- Material examined. One specimen; OMNH-Iv 8434; R = 50 ka et al. 1991: 97; Chao, 2000: 281–282. mm, r = 34 mm, R/r = 1.4; Sakai Fishing Port, Minabe-cho, Material examined. Two specimens; OMNH-Iv 8435; R Hidaka-gun, Wakayama Prefecture, Japan; gill net; collected = 230 mm, r = 15 mm, R/r = 15; Sakai Fishing Port, Mina- by Yasuhiko Azuma on November 19, 2017 (preserved in be-cho, Hidaka-gun, Wakayama Prefecture, Japan; gill net; ethanol on October 9, 2019) collected by Sadao Inoue on February 20, 2020. OMNH-Iv Description. Large disk and noticeably short arms with wide 8436; R = 95 mm, r = 10 mm, R/r = 9.5; Sakai Fishing Port, base. Elliptical madreporite with radiating striae situated Minabe-cho, Hidaka-gun, Wakayama Prefecture, Japan; gill approximately one-third r from center of disk. Longest net; collected by Sadao Inoue on March 7, 2019. diameter of madreporite 4 mm. Vertical lateral side of body Description. Arms 8-10 in number, long and slender (Two formed by marginal plates. Eight actinal plates around mouth arms of specimen of OMNH-Iv 8436 broken and lost). Cru- in each interradial area, surrounded by relatively large, coarse ciform principal plates interconnected with thin and slender granules (Fig. 1H). Adambulacral plate armed with 7–10 rod-like plates (Fig. 1L). Principal plates in each carinal line long, flat furrow spines. Just behind furrow spines, 2–3 large, bearing 2 sharp spines encircled