Possible synonymies of Zoanthus (Anthozoa: Hexacorallia) species on the east coast of South Africa with Pacific congeners

Abstract

Zoanthids cover large patches on the rocky shores of KwaZulu-Natal and northern parts of the Eastern Cape, South Africa. No molecular identification has been carried out on these organisms on the South African shoreline. Zoanthus sansibaricus Carlgren, 1900 has a global distribution and has been reported having numerous morphotypes in terms of polyp shape, size, colour and oral disk colour. The molecular characteristics of three Zoanthus species, Z. sansibaricus, Zoanthus durbanensis Carlgren, 1938 and Zoanthus natalensis Carlgren, 1938, were investigated to determine whether they are three separate species or merely morphotypes of one another. Samples were collected between May 2012 and July 2013, ranging from Umgazana (31.7024°S, 29.4175°E) to Ballito (29.5451°S, 31.2160°E) on the east coast of South Africa and at one site in Libanona, Madagascar (25.0421°S, 46.9952°E). Cytochrome oxidase subunit one (COI), mitochondrial 16S ribosomal DNA (mt 16S rDNA) and the nuclear internal transcribed spacer region of ribosomal DNA (ITS rDNA) were used in this study. The COI sequences had little variation between species groups, while the mt 16S rDNA tree showed that Z. sansibaricus matched with sequences of Z. sansibaricus from the Pacific. Zoanthus natalensis formed a haplotype with Zoanthus kuroshio Reimer & Ono, 2006 and Z. durbanensis formed a haplotype with Zoanthus vietnamensis Pax & Müller, 1957. The ITS rDNA sequences were very similar for these four species: Z. natalensis, Z. kuroshio, Z. durbanensis and Z. vietnamensis. The results of this study indicate that Z. natalensis is likely conspecific to Z. kuroshio and Z. durbanensis is likely conspecific to Z. vietnamensis. This is only a tentative hypothesis as no formal morphological analyses were done on proposed conspecifics. This work highlights the potential of synonymies that can be found globally when investigating new areas.