Biogeography 20. 131–132. Sep. 20, 2018

Earliest Japanese record of the invasive European ascidian lepadiformis complex (Urochordata: )

Teruaki Nishikawa* and Hiroshi Namikawa

Department of Zoology, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan

Abstract: Specimens of the invasive European ascidian complex, collected in 1996 from Suruga Bay, Pacific coast of Honshu Island, Japan and held in the National Museum of Nature and Sci- ence, Tsukuba, predate the earliest Japanese record of the complex by 15 years. The specimens are described and the means of introduction and spread of the complex in Japan discussed.

Key words: Clavelina lepadiformis, invasive ascidian, Suruga Bay, dispersal

Introduction from a wood storage area, Orido Bay, Shimizu Har- bor, Shizuoka Prefecture, Japan, ca. 3 m deep, 2 June The Atlantic clade of the European ascidian, 1996, Kazunari Ogawa coll. by SCUBA (forma- Clavelina lepadiformis (Müller, 1776) species com- lin-fixed, 70% ethanol-preserved). plex sensu Turon et al. (2003) was first recorded in Description. Zooids with enclosing tunic, 9.0 to Japanese waters in 2011, from Nishi-izu, Suruga 27.0 mm long, almost completely separated but unit- Bay, Honshu Island, subsequently being collected ed posteriorly by thin stolons. Many stolonic buds from many fishing ports within the bay (Nishikawa, containing opaque white material; no minute zooids 2017). However, examples of the complex, collected developing from buds. Thorax ca. one-third zooid in 1996 from Orido Bay, Shimizu Harbor (Suruga length, with elongated abdomen posteriorly. Larger Bay), recently found in the ascidian collection of the zooids with many embryos and pre-hatched larvae, National Museum of Nature and Science, Tsukuba up to 0.2 mm diameter, in right peribranchial cavity. (NSMT-Pc), may shed new light on the introduction Thoracic musculature comprising thin longitudinal and subsequent spread of this invasive species along bundles, five converging to branchial siphon, one or the Japanese coast. The specimens are described two to atrial siphon. Stigmatal rows 14 to 16, up to herein. 50 stigmata in each half row. Stomach and adjoining loop of intestine occupying posterior 40 % of abdo- Taxonomic account men, with testicular follicles, but no ovarian eggs, in Clavelina lepadiformis (Müller, 1776) larger zooids. species complex Remarks. An in situ photograph reference of the present specimens indicates life coloration closely Material examined. NSMT-Pc 2887, 20 zooids consistent with that shown in previous descriptions ——————————————————————— of C. lepadiformis given by Berrill (1950, pp. 70-73, *Corresponding author: [email protected] text-figs. 14-15) and Brunetti (1987, pp. 102-103, pl.

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2, pl. 6, b, b1, pl. 7, 1). Having been formalin-fixed, Reference the specimens are now referable only to C. lepadi- formis complex, as further detailed classification is Berrill, N. J., 1950. The Tunicata with an Account of possible only from mitochondrial COI sequence data the British Species. 354 pp. Ray Society, London. (see Turon et al., 2003). Brunetti, R., 1987. Species of Clavelina in the Med- The earliest Japanese record to date of the com- iterranean Sea. Ann. Inst. Océanogr. Paris, 62: plex (2011, off Nishi-izu, Suruga Bay, 28 m; Nishi- 101-118. kawa, 2017) is preceded by the present material (from Nishikawa, T., 2017. Chapter 26. of as- Orido Bay) by 15 years. Most recently, it has been cidians (Urochordata: Ascidiacea) in Japan: past, recorded from Oishi Port, Sumoto, SE Awaji-shi- present, and future. In Motokawa, M. & Kajihara, ma Is (Osaka Bay) (coll. 2012), over 300 km from H. (Eds), Species Diversity of in Japan, Suruga Bay (Nishikawa et al., 2018). The complex Diversity and Commonality in Animals: 679-702. has also been recorded from the Korean coast (2008) Springer Japan, Tokyo. (Pyo and Shin, 2011). Nishikawa, T., Maeda, K. & Okuno, J., 2018. List of It is possible that the complex in Japanese waters ascidians deposited in the Coastal Branch of Nat- was first introduced by foreign vessels to Orido Bay ural History Museum and Institute, Chiba. Nanki- (innermost part of Shimizu Harbor, Suruga Bay), seibutu, 60: 116-119. an area of extensive storage areas for imported Otani, M., 2002. Appearance and latest trends of wood until 2006, but now replaced by pleasure boat introduced marine sessile animals in Japanese wa- marinas (http://www.city.shizuoka.jp/000077737. ters. Sessile Organisms, 19: 69-92. pdf#search=%27%E6%8A%98%E6%88%B8%E6 Pyo, J. & Shin, S., 2011. A new record of invasive %B9%BE+%E8%B2%AF%E6%9C%A8%E5%A0 alien colonial Clavelina lepadiformis %B4%27, available on March 2, 2018). Subsequent- (Ascidiacea: : ) in ly, pleasure boats may have transported the complex Korea. Korean J. Syst. Zool., 27: 197-200. further afield in Suruga Bay or beyond. Orido Bay Turon, X., Tarjuelo, I., Duran, S. & Pascual, M., is also the first recorded Japanese occurrence of 2003. Characterising invasion processes with the West Indian mussel Mytilopsis sallei (Récluz, genetic data: an Atlantic clade of Clavelina lep- 1849) in 1974, probably also introduced by foreign adiformis (Ascidiacea) introduced into Mediterra- wood-carrying ships (see Otani, 2002). Further nean harbours. Hydrobiologia, 503: 29-35. reconstruction of the spread of the Clavelina lepadi- formis complex within Japanese waters, especially (Received March 10, 2018; Accepted May 6, 2018) in the vicinity of Osaka Bay, should be possible if additional museum specimens are found.

Acknowledgements

Sincere thanks are due to Dr Kazunari Ogawa (Z. Nakai Laboratory, Tokyo) for the specimens, and to Dr Graham S. Hardy (Ngunguru, New Zealand) for assistance with English.

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