Debating Phylogenetic Relationships of the Scleractinian Psammocora: Molecular and Morphological Evidences
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Contributions to Zoology, 76 (1) 35-54 (2007) Debating phylogenetic relationships of the scleractinian Psammocora: molecular and morphological evidences Francesca Benzoni1, Fabrizio Stefani1, Jaroslaw Stolarski2, Michel Pichon3, Guillaume Mitta4, Paolo Galli1 1 Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza, 2. 20126 Milano, Italy, [email protected] ; 2 Instytut Paleobiologii PAN, ul. Twarda 51/55, PL-00-818 Warszawa, Poland, [email protected]; 3 Laboratoire des Ecosystèmes Aquatiques Tropicaux et Méditerranéens, Ecole Pratique des Hautes Etudes, Université de Perpignan, 66860 Perpignan Cedex, France; 4 Laboratoire de Parasitologie Fonctionnelle et Évolutive, UMR 5555 CNRS, Université de Perpignan, Perpignan, France Key words: Psammocora, Siderastreidae, Fungiidae, synapticulae, fulturae, ITS, statistical parsimony Abstract SEM preparation and analysis ............................................... 38 DNA extraction, amplifi cation and sequencing ................. 38 The phylogenetic relationships of the scleractinian genus Psam- Network building and distances calculation ....................... 39 mocora with the other genera traditionally included in the fam- Results ............................................................................................... 39 ily Siderastreidae and some Fungiidae are assessed based on Morphology of Psammocora ................................................. 39 combined skeletal and molecular data. P. explanulata differs Polyp morphology .............................................................. 39 from the other examined congeneric species (P. contigua, P. Skeletal structures ............................................................... 40 digitata, P. nierstraszi, P. profundacella, P. superfi cialis, and P. Skeletal structures of the Siderastreidae .............................. 41 stellata) in possessing interstomatous septa between adult coral- The molecular approach ................................................................ 45 lites, costae, and in having continuous buttress-like structures Discussion ........................................................................................ 48 joining septal faces (i.e., fulturae) which typically occur in Skeletal structures ..................................................................... 48 fungiids. These characters are shared with Coscinaraea wellsi Colony wall (epitheca, complex wall structures, but not with the remainder of the examined siderastreids (the septotheca) ........................................................................... 48 congeneric C. columna, and Anomastraea irregularis, Horastrea Calice thecal structures (synapticulae, fulturae, indica, Pseudosiderastrea tayamai, Siderastrea savignyana) adtrabecular bars) ............................................................... 49 whose septa are interconnected by typical synapticulae. Most of Septal microarchitecture and microstructure ................ 49 the examined species form septa with distinct transverse groups Phylogeny of Psammocora and the Siderastreidae ................. 50 of centers of calcifi cation, a biomineralization pattern typical of Conclusions ...................................................................................... 51 the Robusta clade. The observations on skeletal structures cor- Acknowledgements ........................................................................ 52 roborate the results of the ITS2 and 5.8S molecular phylogeny. References ........................................................................................ 52 C. wellsi and P. explanulata are phylogenetically very close to each other and show closer genetic affi nity with the examined Fungiidae (Halomitra pileus, Herpolitha limax, Fungia paumo- Introduction tensis, and Podabacia crustacea) than with the other species in the genera Psammocora and Coscinaraea, or with any other The Indo-Pacifi c coral genus Psammocora Dana, 1846 siderastreid. Our results show that neither Psammocora nor Coscinaraea are monophyletic genera. The high genetic dis- has a wide geographic distribution and it is commonly tances between the species of Siderastreidae, especially between found in any reef environment, from seagrass beds and Pseudosiderastrea tayamai and Siderastrea savignyana on one lagoons, to outer reef slopes down to 50 m depth. Most side and the other genera on the other, suggest a deep divergence species may be cryptic even if some branching species in the phylogenetic structure of the family. can be locally abundant and form monospecifi c stands (Sheppard and Sheppard, 1991; Veron, 2000). Skeletal structures in Psammocora are complex and plastic, and Contents some characteristic morphological features unique to the genus such as extrapolypal tentacles, and the intri- Introduction ...................................................................................... 35 cate mesh of ento- and exosepta (Matthai, 1948a; Mat- Material and methods ..................................................................... 37 thai, 1948b) have been largely overlooked in the litera- Species identifi cation ............................................................... 37 Choice of Psammocora species ............................................. 37 ture thus leading to the use of confused terminology in Sampling ..................................................................................... 38 descriptions by various authors. 36 F. Benzoni et al. – Phylogenetics of the scleractinian coral Psammocora Twenty-three extant Psammocora species have been Coscinaraea Milne Edwards and Haime, 1848, Ano- described. Many of those have been put in synonymy mastraea Marenzeller, 1901, Pseudosiderastrea Yabe (Veron and Pichon, 1976; Scheer and Pillai, 1983; Shep- and Sugiyama, 1935, and Horastrea Pichon 1971 (Fig. pard and Sheppard, 1991). A global revision of the 1d). These genera have been grouped together because genus, however, has never been undertaken. Eleven of the common presence of synapticulae and the fusion Psammocora species are listed in Cairns et al. (1999), of septa around the corallite fossa. A comprehensive and Veron (2000) retains twelve species. However spe- treatment of the family skeletal structures, however, cies synonymies are not indicated or discussed in either has never been published, and such characters have publication. never been proved to be plesiomorphic. The genus Hypotheses about phylogenetic relationships of Craterastrea Head, 1983 is poorly known and pres- Psammocora and the resulting classification have ently recorded from the Red Sea and Chagos only changed dramatically over the last sixty years (Stolarski (Head, 1983; Sheppard, 1981; Sheppard, 1998; Shep- and Roniewicz, 2001). Vaughan and Wells (1943) con- pard and Sheppard, 1991). It was described as a sid- sidered Psammocora the only extant genus in the erastreid and has been later synonymised with the Thamnasteriidae, suborder Fungiida (Fig. 1a), based on agariciid genus Leptoseris (Veron, 1995; Veron 2000; the presence of synapticulothecal wall and simple Inskipp and Gillett 2005). trabeculae of septa. Alloiteau (1952) also placed Psam- Among the extant corals Psammocora bears struc- mocora, Stephanoseris and Plesioseris in the family tural similarities to Coscinaraea especially in the septa Thamnasteriidae. Wells (1956) still maintained Psam- shape and corallites arrangement (Pandolfi, 1992; mocora in the Thamnasteriidae, but placed the family Veron, 2000), and to Craterastrea. Coscinaraea co- in the Astrocoeniina (Fig. 1b). Chevalier and Beauvais lumna (Dana, 1846) and Coscinaraea exesa (Dana, (1987) brought back the Thamnasteriidae in the Fun- 1846) were originally described as Psammocora, and giina but placed Psammocora in the new family Psam- the similarities between Psammocora explanulata Van mocoridae (Fig. 1c) along with Stephanaria Verrill, der Horst, 1922, and Coscinaraea wellsi Veron and 1867, and Plesioseris Duncan 1884, both previously Pichon, 1980 are evident (Veron and Pichon, 1980; considered subgenera of Psammocora, and synonymised Veron, 2000). Morphologic affi nities of the septa fusion with it by Veron and Pichon (1976). Finally Veron patterns in Psammocora and in the fungiids Lithophyl- (1995) based on skeletal features and on its “clear af- lon Rehberg, 1892 and Polyphyllia Blainville, 1830 fi nities” with Coscinaraea classifi ed Psammocora in have also been remarked (Veron and Pichon, 1976; Van the Siderastreidae with Siderastrea Blainville, 1830, der Horst, 1922). Fig. 1. Changes in classifi cation of the genus Psammocora. Grey arrows indicate the change of position of the genus (in bold italic) within a family (in bold) and suborder (in bold capitals) according to a) Vaughan and Wells (1943), b) Wells (1956), c) Chevalier et Beauvais, 1987, d) Veron (1995). Modifi ed from Stolarski and Roniewicz (2001). Contributions to Zoology, 76 (1) – 2007 37 The molecular phylogeny of the Fungiina has, so far, preserved material nor to collect it. Our data on the been only partially investigated. Studies based on mi- genus is therefore limited to the external skeletal struc- tochondrial DNA (Romano and Palumbi, 1996; Romano tures. For the identifi cation of the Fungiidae species and Cairns, 2000) showed that the Fungiina are not Halomitra pileus (Linnaeus, 1758), Podabacia crusta- monophyletic and that Psammocora stellata and Cosci- cea (Pallas, 1766), Herpolitha limax Esper, 1797, and naraea sp., cluster