Biogeography 22. 53–57. Sep. 20, 2020

New distributional records of three 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 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 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) 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 by wreath of crossed pedicel- domed subambulacral spines covered with coarse granules. lariae covered by thick membrane. Small adambulacral plates These subambulacral spines in very close contact with each with 2 slender spines: a furrow and a subambulacral spine other, forming massive bumped shape. Between adambulacral (Fig. 1M). Series of crossed pedicellariae along furrow. Large plates, one large, lanceolate pedicellariae (Fig. 1I). multi-clawed, uniguiculated pedicellariae rarely occurring on Color in life. The abactinal surface is reddish-brown and adambulacral plate. the plates around the edges are dark reddish-brown. The Color in life. The abactinal surface is vivid vermilion. The

– 55 – Three sea stars from the coast of the Kii Peninsula actinal surface is pale cream. low-water Indo-West Pacific echinoderms. Trusties of the Distribution. Type locality: Kagoshima Bay (SE Japan) at British Museum of Natural History, London, 238 pp. depth of 40 m (Döderlein, 1902). Also known from Taiwan Clark, H. L., 1914. The echinoderms of the Western Australian (Chao, 2000), Sagami Bay, the East China Sea (Imaoka et al., Museum. Records of the Western Australian Museum and 1991), and Minabe, Wakayama Prefecture (present study). Art Gallery, 1 (3): 132–173. Remarks. This sea star is characterized by 10 long slender Clark, H. L., 1946. The echinoderm fauna of Australia. Its arms, 2 adambulacral spines, and crossed pedicellariae along composition and its origin. Carnegie Institution of Washing- the furrow; these features are consistent with those described ton Publication, 566: 1–567. by Imaoka et al (1991). Two congenic species C. volsellatus Döderlein, L., 1902. Japanische Seesteme. Zoologischer An- (Sladen, 1889) and C. pauciporis Jangoux, 1984 are also zeiger, 25: 326–335. known from Japanese waters (Kogure, 2018). Coronaster Döderlein, L., 1935. Die Asteriden der Siboga-Expedition. III. sakuranus is distinguished from both species based on the Oreasteridae. Siboga-Expedition, 46 (3): 71–110. following external features: a single adambulacral spine Fisher, W.K., 1913. Four new genera and fifty-eight new spe- of C. volsellatus, and no uniguiculated pedicellariae of C. cies of from the Philippine Islands, Celebes, and pauciporis. the Moluccas. Proceedings of the United States National Museum, 43: 599–648. Acknowledgements Hayashi, R., 1943. Contributions to the classification of the sea-stars of Japan. 2. Forcipulata, with the note on the re- We would like to thank all the staff of the Shirahama lationships between the skeletal structure and respiratory Aquarium, Kyoto University, for their invaluable assistance organs of the sea-star. Journal of the Faculty of Science, during this study. We are grateful to Dr. Masanori Okanishi (the Hokkaido University, 6: 133–281. University of Tokyo) for his critical reading of the manuscript. Hayashi, R., 1973. The sea-stars of Sagami Bay: Collected by The authors appreciate the help of Mr. Sadao Inoue and Mr. His Majesty the Emperor of Japan. Biological Laboratory, Yasuhiko Azuma in collecting the specimens. Mr, Nakachi Imperial Household of Japan, Tokyo, 114 pp. (in English), (Natural History Lab.) gave us a part of the data. We thank 89 pp. (in Japanese) Dr. So Ishida (Osaka Museum of Natural History), who was Imaoka, T., Irimura, S., Okutani, T., Oguro, C. Oji, T. & willing to deposit the examined specimens in the museum. We Kanazawa, K., 1991. Echinoderms from continental shelf also extend our gratitude to the reviewers for their useful sug- and slope around Japan. Vol. II. Japan Fisheries Resource gestions. Conservation Association Press, Tokyo, 203 pp. Jangoux, M., 1986. Les astérides, pp. 109–153. In: Guille, References A. et al. (Eds.) Guide des étoiles de mer, oursins et autres échinodermes du lagon de Nouvelle-Calédonie. ORSTOM, Baker, A. N. & Marsh, L. M., 1976. The rediscovery of Hali- Paris. tyle regularis Fisher (Echinodermata: Asteroidea). Records Kogure, Y., 2018. A checklist of sea stars (Echinodermata, of the Western Australian Museum, 4 (2), 107–116. Asteroidea) from Japanese waters. Bulletin of the Biogeo- Chao, S. M., 2000. New records of Sea Stars (Asteroidea: graphical Society of Japan, 73: 70–86. (in Japanese with Echinodermata) from the Continental shelf of Taiwan. Zoo- English abstract) logical Studies, 39 (3): 275–284. Kogure Y. & Igei, H., 2013. First record of the large tropical Clark, A. M., 1993. An index of names of recent Asteroidea. oreasterid sea star Poraster superbus (Echinodermata, As- Part 2: Valvatida. pp. 187–366. In: Jangoux, M. & Law- teroidea) from Japanese waters. Biogeography, 15: 33–36. rence, J.M. (eds.), Echinoderm Studies, 4. A. A. Balkema, Kogure, Y. & Kaneko, A., 2018. First record of goniasterid sea Rotterdam. star Glyphodiscus perierctus (Echinodermata, Asteroidea, Clark, A. M. & Downey, M. E., 1992. Starfishes of the Atlan- Valvatida) from Japan. Bulletin of the Biogeographical tic. Chapman & Hall Identification Guides, 3. Chapman & Society of Japan, 72: 204–208. (in Japanese with English Hall, London, 794 pp. abstract) Clark, A. M. & Mah, C., 2001. An index of names of recent Kogure, Y., Kohtsuka, H. & Kiyomoto, S., 2012. First record asteroidea. Part 4: and Brisingida. pp. 229– of the ophidiasterid sea star, Ophidiaster multispinus (Echi- 347. In Jangoux, M. and Lawrence , J. M. (Eds), Echino- nodermata, Asteroidea), from Japan, with reference to the derm Studies, 6. Swets & Zeitlinger B. V., Lisse. wide intraspecific variations in external features. Biogeog- Clark, A. M. & Rowe, F. W. E., 1971. Monograph of shal- raphy, 14: 133–138.

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(Received June 17, 2020; Accepted July 21, 2020)

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