Molecular and morphological evidence for conspecificity of two common Indo-Pacific species of Palythoa (Cnidaria: Anthozoa) Yuya Hibino, Peter A. Todd, Sung-yin Yang, Yehuda Benayahu & James Davis Reimer Hydrobiologia The International Journal of Aquatic Sciences ISSN 0018-8158 Hydrobiologia DOI 10.1007/s10750-013-1587-5 1 23 Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Hydrobiologia DOI 10.1007/s10750-013-1587-5 BIODIVERSITY IN ASIAN COASTAL WATERS Molecular and morphological evidence for conspecificity of two common Indo-Pacific species of Palythoa (Cnidaria: Anthozoa) Yuya Hibino • Peter A. Todd • Sung-yin Yang • Yehuda Benayahu • James Davis Reimer Received: 24 February 2013 / Accepted: 2 June 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Zoanthids of the genus Palythoa are possibility that these species are in fact one. Based on common in coral reef environments worldwide, par- specimens from Australia, the Red Sea, and Japan, we ticularly in the intertidal zone. However, their taxon- used three DNA markers (mitochondrial cytochrome omy remains problematic, resulting in an incomplete oxidase I, 16S ribosomal DNA, and the nuclear understanding of their diversity. Palythoa caesia internal transcribed spacer region of ribosomal Dana, 1846 is found in Fiji, Australia, and the Indian DNA) combined with morphological analyses of Ocean, while P. tuberculosa (Esper, 1805) has been tentacle numbers, and cnidae to re-examine the reported from India, the Red Sea, Singapore, Mada- identity of these two taxa. Phylogenetic results showed gascar, and Japan. The lack of obvious characters sequences from all specimens for all markers formed differentiating the two species, their wide distributions one monophyly, and morphological results showed and high levels of intraspecific variation raise the little differentiation between the two putative taxa. Overall, it is apparent these two taxa are the same species, and the senior synonym P. tuberculosa should Electronic supplementary material The online version of be used for specimens for the entire Indo-Pacific this article (doi:10.1007/s10750-013-1587-5) contains supple- region. mentary material, which is available to authorized users. Keywords Hexacorallia Á Synonymy Á Guest editors: M. Tokeshi & H. T. Yap / Biodiversity in Changing Coastal Waters of Tropical and Subtropical Asia Taxonomy Á Zoanthid Y. Hibino Á S. Yang Á J. D. Reimer (&) Molecular Invertebrate Systematics and Ecology Introduction Laboratory, Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan Zoanthids of the genus Palythoa Lamouroux, 1816 are e-mail: [email protected] among the most common anthozoans in shallow subtropical and tropical oceans. Like many other P. A. Todd Experimental Marine Ecology Laboratory, National shallow water zoanthids, the majority of species in this University of Singapore, 14 Science Drive 4, Blk S2, genus are zooxanthellate, hosting endosymbiotic #02-02, Singapore 117543, Republic of Singapore dinoflagellate species of Symbiodinium Freudenthal, 1962 (Burnett, 2002; Reimer et al., 2006c). Typical of Y. Benayahu Department of Zoology, Tel Aviv University, zoanthids, Palythoa spp. have their tentacles arranged 69978 Tel Aviv, Israel in two rows around their oral disk, and are encrusted 123 Author's personal copy Hydrobiologia with sand and detritus. Palythoa spp. are particularly synonymized this species with P. flavoviridis Ehren- encrusted, with up to 65% of their body weight made berg, 1834 and P. argus Ehrenberg, 1834. According up of foreign materials (Haywick & Mueller, 1997). to Klunzinger’s (1877) redescription, P. tuberculosa Historically, species of Palythoa have been inhabits the surf zone, with colonies 5–20 mm in described and identified based on the morphology thickness and having an uneven, brown surface. (including size and coloration) of polyps and colonies, Polyps possess 30–40 tentacles, are 1–6 mm in height as well as on the development and shape of their and 5–7 mm in diameter, although it is not clear sphincter muscles. Currently, there at least 107 whether Klunzinger referred to dried, preserved, or nominal species of Palythoa mentioned in the litera- live specimens. P. tuberculosa is currently used ture (Reimer 2012). Many species of Palythoa were throughout much of the Indo-Pacific, and is mentioned described in the twentieth century, primarily by Pax in literature and guide books from the Red Sea (30 species described between 1908 and 1957) and (Erhardt & Knop, 2005; Polak et al., 2011), Oman Carlgren (20 species described between 1900 and (Erhardt & Knop, 2005), the Maldives (Erhardt & 1952) as both of them examined specimens from Knop, 2005), India (Esper, 1805), New Caledonia expeditions to various parts of the world (e.g., West (Sinniger, 2006), Singapore (Reimer & Todd, 2009), Africa, Australia). However, it is likely that the true Palau (Erhardt & Knop, 2005), Taiwan (Reimer et al., number of species is much lower due to high levels of 2011), Japan (Yamazato et al., 1973; Reimer et al., morphological variation within species and inadver- 2006b, c, 2007b), Hawaii (Hoover, 1999), and the tent redescriptions (Burnett et al., 1997; Reimer et al., Galapagos (Reimer & Hickman, 2009). 2004). Asides from some research by Ryland and co- Palythoa caesia was described from Fiji by Dana workers (e.g., Ryland & Lancaster, 2003), there has (1846) as having ‘immersae’, dark brown colonies been no major taxonomic revision of this group since with uneven surfaces, and many tentacles (the number the first half of the twentieth century. A complete was not specified). This binomen is most commonly understanding of Palythoa spp. diversity is impossible applied in Australia (Burnett et al., 1994, 1997), and until a comprehensive reassessment addresses the has also been used in the Indian Ocean (Burnett, abnormally elevated ‘‘synonymy load’’ in this group 2002), Papua New Guinea (Erhardt & Knop, 2005), (Low & Reimer, 2011). Guam (Paulay et al., 2003), and Hawaii (Hoover, Within Palythoa, two of the most commonly used 1999). binomens in the Indo-Pacific are Palythoa tuberculosa Examining the total descriptive data for P. tuberculosa (Esper, 1805) and Palythoa caesia Dana, 1846 (Fig. 1; from Esper (1805), Ehrenberg (1834), and Klunzinger Table 1). Both species are zooxanthellate, have heavy (1877), and P. caesia from Dana (1846), it is impossible sand encrustation and an ‘‘immersae’’ gross colony to clearly distinguish these two species except by locality morphology with polyps deeply embedded in a well- (Table 1),andeventhisisconfusedincertainregions developed coenenchyme (Pax, 1910). Different Indo- such as Hawaii, and in some publications (e.g. Fossa & Pacific regions apply one of the two binomens, Nilsen, 1998). This problem is specifically mentioned by although there are some regions where both are used. Hoover (1999), who notes that due to identification No obvious morphological differences exist between difficulties, both binomens are used in Hawaii. the two species (Fig. 1; Table 1) and typify a common Past analyses of Palythoa spp. using molecular problem in zoanthid taxonomy, that is, the lack of methods have indicated that individual species may accurate species level diagnostic characters (e.g., encompass a wide variety of morphologies (Burnett Swain, 2010). et al., 1994, 1997; Reimer et al., 2006a) over a wide Palythoa tuberculosa (Esper, 1805) was originally distribution range, raising the possibility that P. described as Alcyonium tuberculosum from specimens tuberculosa and P. caesia are in fact the same species (since lost) collected in Tranquebar (now Tharangam- (Sinniger, 2006). The two binomens have been in badi), India, as colonies with a leather-like surface and common use for over 150 years, and resolving their ocher coloration. In 1834, Ehrenberg described two identity is of importance not only for the taxonomy of similar species, P. flavoviridis and P. argus, from the Palythoa, but also for understanding their diversity Red Sea. After this, Klunzinger (1877) redescribed P. and distribution in the Indo-Pacific. Here, we examine tuberculosa from specimens in the Red Sea, and specimens from the ranges of both species utilizing 123 Author's personal copy Hydrobiologia Fig. 1 Original description drawings and in situ images of A, collected), and D P. caesia specimen Heron91 from Broomfield C Palythoa tuberculosa (Esper, 1805) and B, D P. caesia Dana, Reef, near Heron Island, Great Barrier Reef, Australia, depth 1846. A P. tuberculosa from original description in Esper 2 m. Note both P. tuberculosa and P. caesia have large varieties (1805) (Table XXIII), and B drawing of P. caesia by Dana of color variation (light tan to dark brown,