Contributions to Zoology, 80 (4) 231-249 (2011) Phylogeny of the coral genus Plesiastrea (Cnidaria, Scleractinia) Francesca Benzoni1, 2, 4, Roberto Arrigoni2, Fabrizio Stefani2, Michel Pichon3 1 Institut de Recherche pour le Développement, UMR227 Coreus2, 101 Promenade Roger Laroque, BP A5, 98848 Noumea Cedex, New Caledonia 2 Dept. of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy 3 Museum of tropical Queensland, Townsville 4810, Australia 4 E-mail: [email protected] Key words: COI, Plesiastrea versipora, Plesiastrea devantieri, rDNA, robust clade Abstract DNA extraction, amplification and sequencing ............... 235 Phylogenetic analyses ............................................................ 236 Until coral molecular phylogenies were published, the genus Results ............................................................................................. 237 Plesiastrea was traditionally part of the family Faviidae and Macromorphology .................................................................. 237 considered by several authors to be closely related to the genus Micromorphology ................................................................... 239 Montastraea. However, genetic data has shown that Plesiastrea COI phylogeny ......................................................................... 239 versipora, the genus type species, is evolutionarily distinct with- rDNA phylogeny ...................................................................... 239 in the Robust clade of the Scleractinia and does not belong to the Discussion ...................................................................................... 241 large clade grouping most representatives of the families Favii- Polyphyly of the genus Plesiastrea ...................................... 241 dae, including Montastraea, Mussidae, Merulinidae, Trachy- Phylogenetic relationships of Plesiastrea versipora ........ 244 phylliidae, and Pectiniidae. Instead, P. versipora is closely re- Phylog enetic relationships of Plesiastrea devantieri lated to non reef-dwelling taxa currently ascribed to the Oculi- and implications for taxonomy ............................................ 246 nidae (Cyathelia axillaris) and Caryophylliidae (Trochocyathus Acknowledgements ...................................................................... 246 efateensis). However, no discussion on the morphologic features References ...................................................................................... 247 of P. versipora compared to other taxa has been published yet. Moreover, no information is available about the phylogenetic placement of Plesiastrea devantieri, the only other species in the genus. The phylogeny of both Plesiastrea species was addressed Introduction through molecular analyses (COI and rDNA) and morphologi- cal analysis. Morphological differences between the two species Scleractinian corals (Cnidaria, Scleractinia) belong to included number of septa, cycles of vertical structures in front of two main molecularly defined clades (Romano and the septa and septal micromorphology. On the basis of these data Palumbi, 1996), the Robust and the Complex clade, and nuclear and mitochondrial markers, P. devantieri belongs to the Faviidae-Merulinidae-Pectiniidae-Trachyphylliidae clade and most families and genera as traditionally defined (Clade XVII sensu Fukami et al., 2008) and is most closely re- on the basis of skeleton macromorphologic characters lated to Goniastrea aspera and G. palauensis. The type species are polyphyletic (Fukami et al., 2004, 2008; Benzoni of the genus Goniastrea, G. retiformis, however, is not closely et al., 2007; Nunes et al., 2008; Huang et al., 2009, related to either G. aspera and G. palauensis, or to P. devantieri. 2011; Kitahara et al., 2010a). Moreover, Kitahara et al. Taxonomic implications of these findings and morphologic af- finities between the two species and closely related taxa are dis- (2010a) recently showed that azooxanthellate solitary cussed. corals from deep-water form a clade basal to both the Robust and the Complex corals. In other words, mo- lecular phylogenies of scleractinian corals and tradi- Contents tional taxonomy and systematics based on skeleton morphology are, to a large extent, incompatible. Rec- Introduction .................................................................................... 231 onciliation of these two approaches is ongoing, but Material and methods ................................................................... 233 presently the need for an integrative approach which Sampling ................................................................................... 233 includes molecular, macrostructural, microstructural, Specimen identification .......................................................... 235 Museum collections and other examined specimens ....... 235 reproductive and ecological analyses is required (Budd Morphologic analyses ............................................................ 235 and Stolarski, 2009; Budd et al., 2010). In addition, Downloaded from Brill.com09/25/2021 03:07:13PM via free access 232 Benzoni et al. – Phylogeny of the coral genus Plesiastrea shallow water, deep water, colonial, solitary, tropical form lobe is a PS formed by a single center of rapid and temperate taxa should all be included in the analy- accretion stemming from the inner end of a septum ses to determine the evolutionary history of this an- (Chevalier and Beauvais, 1987). cient group (Romano and Cairns, 2000; Le Goff-Vitry The genus Plesiastrea was originally described by et al., 2003; Barbeitos et al., 2010; Kitahara et al., Milne-Edwards and Haime (1848) on the basis of a 2010b). specimen from the Indian Ocean named Astrea versi- One of the most challenging tasks in the taxonomy pora by Lamarck (1816). The main characters of the of the shallow water zooxanthellate corals is the revi- genus were described as plocoid corallites, presence of sion of the family Faviidae Gregory, 1900 which, to- pali sensu stricto, and the extracalicinal mode of coral- gether with the Merulinidae Verrill 1866, Mussidae lite budding. The species Plesiastrea urvillei Milne- Ortmann, 1890, Trachyphyliidae Verrill, 1901, and Edwards and Haime, 1849, and P. quatrefagiana Pectiniidae Vaughan and Wells, 1943, are found in the Milne-Edwards and Haime, 1849, were also ascribed Robust clade (Fukami et al., 2004, 2008; Kitahara et to the genus but both may be junior synonyms of P. al., 2010b). Despite a deep divergence between Atlan- versipora (Veron et al., 1977). According to Chevalier tic and Indo-Pacific taxa in both the Mussidae and (1971) the main skeletal character distinguishing Ple- Faviidae (Fukami et al., 2004), most genera from these siastrea from the other genera is the presence of pali as families were retrieved in several closely related clad- opposed to paliform lobes in the other Faviidae such es. The genera Cladocora Ehrenberg, 1834, Oulastrea as, among the others, Montastraea and Goniastrea. Milne-Edwards and Haime 1848, Leptastrea Milne- Plesiastrea has presumably remained monotypic for Edwards and Haime 1848, and Plesiastrea Milne-Ed- decades until the description of P. devantieri on the wards and Haime 1848, however, are not closely re- basis of specimens from Socotra Island, Yemen (Ve- lated to the remainder of the Faviidae, nor to one an- ron, 2000, 2002). In his original description Veron other (Fukami et al., 2008; Barbeitos et al., 2010). (2002) did not provide details on the micromorpho- Plesiastrea is clearly distinct and divergent from the logical characters of P. devantieri and species phylo- rest of the Faviidae (Fukami et al., 2008). Despite genetic relationships were not examined. strong morphologic affinities (Vaughan and Wells, Morphological affinities between Plesiastrea and 1943; Wells, 1956; Chevalier, 1971; Wijsman-Best, Montastraea and nomenclatural confusion between 1977; Veron et al., 1977; Chevalier and Beauvais, the two taxa and Orbicella, a junior synonym of Mon- 1987), no close phylogenetic relationship has been tastraea (Wijsman-Best, 1977) on the one hand, and found between Plesiastrea and the genus Montastraea Favia on the other hand, have been discussed by Wijs- de Blainville, 1830, the latter actually being polyphyl- man-Best (1977) and Veron et al. (1977) who provided etic (Fukami et al., 2004, 2008; Huang et al., 2009). detailed accounts of the history of nomenclatural con- Different vertically developed skeletal structures fusion between those genera. Although Plesiastrea is are found in the corallites of scleractinian corals. Their superficially similar to Cyphastrea (Veron, 2002) no origin, structure, number, size, and shape have been nomenclatural confusion occurred between the two used for taxonomy and systematics (Vaughan and taxa. Chevalier (1971) described transitional morphs Wells, 1943). The principal ones are the septa (radially between P. versipora and M. curta. The latter species arranged around the centre of the corallite) and, if pre- was first ascribed to Orbicella by Dana (1846) and sent, the columella (found at the centre of the corallite) later moved to the genus Montastraea whose type spe- (Vaughan and Wells, 1943; Chevalier and Beauvais, cies, Astrea guettardi Defrance, 1830, is a fossil. Ac- 1987). In certain taxa a third type of vertical skeletal cording to Wijsman-Best (1977) some specimens structure can exist between the inner margin of the identified as