Possible synonymies ofZoanthus(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 & M€ uller, 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.

Assessing the Zoantharian Diversity of the Tropical Eastern Pacific through an Integrative Approach

“…Therefore, identification at species level remains a true challenge 21 and molecular approaches have recently been applied to revise this complex order 16 , 18 , 22 – 25 . While this approach has become the main source of evidence supporting the discovery and description of higher taxa and species 18 , 24 , 26 – 28 , relationships between closely related species remain largely unresolved 25 , 29 . Given that the history of zoantharian taxonomy leaves many gaps, including poorly characterized taxa 13 with inconsistent molecular and ecological data, and also discrepancies between morphological and DNA-based taxonomy 18 , 24 , 30 – 32 , we decided to add metabolomic data to shed light on this confused situation and contribute to the development of an integrative systematics of the order Zoantharia.…”

Update on the distribution of Isaurus tuberculatus Gray, 1828 (Cnidaria, Zoantharia) and first insight into the microanatomy and cnidom of South Atlantic populations

“…As previously discussed, the elevated variability within clusters and between populations, both in the Atlantic (confirmed in this present study) and in the Indo-Pacific does not permit the separation of species. Until now, molecular studies with populations in Florida, Cape Verde Islands, Saint Helena, and West Africa found congruence between the sequences collected and the I. tuberculatus populations in Japan (Reimer et al 2010(Reimer et al , 2012Risi and Macdonald 2015;Santos et al 2019). However, results differed according to the molecular marker used, and although the molecular analyses indicated co-specificity, the authors of these studies acknowledged the improbability of this based on the absence of a zooxanthellate species inhabiting the Atlantic and Indo-Pacific.…”

“…Approaches using zooxanthellae may help to identify cryptic species and to delimit species (Risi and Macdonald 2015). However, populations of I. tuberculatus in Japan, Cape Verde Islands, and West Africa (Reimer 2008b;Reimer et al 2011a;Risi 2014;Risi and Macdonald 2015) present Symbiodinaceae of the subclades C1/C3 (currently Cladocopium). Several species in this group are highly generalist and are also found in other zoantharian genera (Reimer et al 2008b).…”

“…Since Muirhead and Ryland's (1985), many new locations in the Atlantic have been reported: Ascension Island (Brown et al 2016), Brazil (Grohmann andPeixinho 1995;Soares et al 2011;Santos et al 2016;Gondim et al 2020), Canary Islands (Riera et al 2014;López et al 2019), Cape Verde (Reimer et al 2010), Cuba (Varela et al 2002;Diez and Campos-Castro 2016), Curaçao and Saint Eustatius (Montenegro et al 2020), Saint Helena (Santos et al 2019), Florida, USA (Reimer et al 2012), Caribbean Colombian and other areas in the Caribbean (Acosta et al 2005), São Tomé and Principe (Wirtz 2018), andMexican Caribbean (Fautin andDaly 2009). In the Indo-Pacific, additional locations have been reported from Palau (Santos and Reimer 2018), India (Khushali et al 2014;Kumari et al 2017), Taiwan (Reimer et al 2011b), Hawaii (Forsman et al 2012), Vietnam (Reimer et al 2015), Indonesia (Sinniger et al 2005), New Caledonia (Laboute and Richer de Forges 2004), Moluccas and Lembeh Strait (Reimer et al 2014), Gaum (Paulay et al 2003), and Japan (Reimer et al 2008a), and in the Indian Ocean, from the east coast of South Africa (Risi 2014;Risi and Macdonald 2015). The global distribution of the species can be accessed through the World Register of Marine Species at https://www.…”

“…Although molecular studies have been carried out with the aim of defining the phylogeny of the genus, the two mitochondrial markers used so far are inadequate to distinguish species within a genus. Furthermore, specific primers for zoantharians from faster evolving markers, such as ITSrDNA, do not work for Isaurus (Reimer et al 2008b;Risi and Macdonald 2015). Therefore, the genus, and particularly I. tuberculatus sensu lato, requires a comprehensive revision, which should include a detailed description of the external morphology, microanatomy, and cnidom, as well as the use of other relatively fastevolving DNA markers, to characterize morphological variation among populations.…”