Porites fontanesii, a new species of hard coral (Scleractinia, Poritidae) from the southern Red Sea, the Gulf of Tadjoura, and the Gulf of Aden, and its phylogenetic relationships within the genus Benzoni, Francesca Stefani, Fabrizio Zootaxa 2012 3447 56 68 4LXSZ [151,363,1842,1868] Anthozoa Poritidae Porites Animalia Scleractinia 2 58 Cnidaria species fontanesii sp. nov.   Material examined. Holotype: MNHN-IK.2009-834 Balhaf, Yemen( 13°58.228’ N; 48°10.759’ E), 5 m, coll. F. Benzoni & M. Pichon, 20/09/2007, collection code BAL085.  Paratypes: MSNMCOE332 Al Mukallah ( 14° 31.059’ N; 49° 10.283’ E), 3.5 mcoll. M. Pichon & F. Benzoni, 17/03/2007, collection code MU003; UNIMIB Y359 Balhaf ( 13°58.163’ N; 48°10.928’ E), 4 m, coll. F. Benzoni, 08/09/05(GenBank accession number HE585991).  Other material: YemenRed SeaUNIMIB KA022 Kamaran Island ( 15°21.988’ N; 42°37.540’ E) F. Benzoni & A. Caragnano, 28/09/2009; KA170 Al Badi' (15°29.573’; 42°32.109’ E) 02/10/2009;  DjiboutiTO-DJ030, Ras Ali, Gulf of Tadjoura, ( 11°46.354’ N; 42°57.286’ E), 7 m, coll. F. Benzoni, 28/01/2010; TO-DJ079, Oblal, Gulf of Tadjoura, ( 11°48.677’ N; 43°3.427’ E), 8 m, coll. F. Benzoni, 29/01/2010; TO-DJ134, Musha, Gulf of Tadjoura, ( 11°44.623’ N; 43°10.116’ E), 10 m, coll. F. Benzoni, 31/01/2010; Ye m e n G u lf o f Ade nUNIMIB Y358 Balhaf ( 13°58.163’ N; 48°10.928’ E) coll. F. Benzoni, 08/09/05(GenBank accession number HE585990); Y360 Balhaf ( 13°58.163’ N; 48°10.928’ E) coll. F. Benzoni, 08/04/06(GenBank accession number HE585992); Y694 Balhaf ( 13°58.402’ N; 48°12.410’ E) coll. F. Benzoni, 10/03/08; BAL015 Balhaf ( 13°58.331’ N; 48°11.164’ E) coll. M. Pichon & F. Benzoni, 04/03/2007; BAL042 ( 13°58.865’ N; 48°10.611’ E) coll. F. Benzoni 20/05/2007; BAL044 ( 13°58.865’ N; 48°10.611’ E) coll. M. Pichon & F. Benzoni 16/09/2007; BAL069 Balhaf ( 13°58.228’ N; 48°10.759’ E) coll. M. Pichon & F. Benzoni, 20/09/2007; BAL108 Balhaf ( 13°58.228’ N; 48°10.759’ E) coll. M. Pichon & F. Benzoni, 20/09/2007; BAL175b Balhaf ( 13°58.163’ N; 48°10.928’ E) coll. M. Pichon & F. Benzoni, 22/09/2007; BAL250 Balhaf ( 13°58.444’ N; 48°11.560’ E) coll. M. Pichon & F. Benzoni, 23/09/2007; MU027 Al Mukallah ( 14° 31.059’ N; 49° 10.283’ E) coll. M. Pichon, F. Benzoni & C. Riva, 17/03/2007; MU091 Al Mukallah (14° 30.923 N; 49° 9.254 E) coll. M. Pichon & F. Benzoni, 17/03/2007; BA092 Sikha Island (13° 55,775 N; 48° 23,219 E) 8 m, coll. F. Benzoni & S. Montano, 21/11/2008(GenBank accession number HE585993);  SocotraIslandUNIMIB SO057 Araher ( 12°34.942’ N; 54°26.004’ E), 18 m, coll. F. Benzoni & A. Caragnano, 13/03/ 2010; SO114 Ras Qadamah ( 12°41.902’ N; 53°39.682’ E) 10 m, coll. F. Benzoni & A. Caragnano 17/03/2010; SMF(housed at EPA Socotra) C90S, ST-145 W Ras Momi, 02/04/1999; C325S, ST-738 Medina, 18/04/2000.  Skeletal characteristics of the holotype.The holotype( Fig. 1) is part of a large colony ( Fig. 1a). The fragment is 9 cmlong, 4.5 cmwide, and 2.5 cmthick. It is characterized by an encrusting base from which three taller digitations and one shorter digitiform non-anastomosing projections develop. Digitations tips are rounded ( Fig. 1A–C). Corallite density over the corallum surface is 50–66 corallites/cm2 ( Fig. 1C–D). Corallites are flush with the coenosteum, although they tend be slightly sunken at the base of the digitations. They are separated by coarsely ornamented coenosteum and can be locally arranged in short series 3 to 6 corallites long ( Fig. 1D). Collines, or ridges, are not present. Calice diameter ranges from 0.9 to 1 mm. A columella is absent. The typical septa arrangement of the genus  Poritesis observed with 12 septa arranged in four lateral pairs, one dorsal septum and three ventral septa ( Fig. 1E; Fig. 2A–B). The dorsal septum is shorter than other septa (larger arrows in Fig. 2B) and the synapticulae connecting it to one of the two lateral pairs, or both, can be more or less visible from the top (smaller arrows in Fig. 2B). The ventral triplet is fused ( Fig. 2B). Five large pali are normally present in corallites, four in front of the four lateral pairs of septa, and one in front of the ventral triplet ( Fig. 2B). No palus is found in front of the short dorsal septum. Upper septal margins carry 1 finely ornamented denticle ( Fig. 2). The innermost circle of synapticulae connecting the pali is visible and can be thin ( Fig. 2A–C) or thick ( Fig. 2D–F). In some corallites it can be so thick to resemble a hollow columellar structure ( Fig. 2E–F). In these corallites an irregular fusion of the ventral triplet can be observed ( Fig. 2F), and two smaller pali or no palus at all can be found in front of it.  Variability.The study of the typeseries and of the other collected specimens showed that although a digitate colony developing from an encrusting base is typical of  Porites fontanesii  sp. nov., a certain degree of variability of the digitations upper ends diameter and shape is observed. These can be circular to oval in section ( Fig. 4) with thickness ranging from 1 to 4 cm. In larger colonies digitations tend to fan out and occasionally branch ( Fig. 3A–D, Fig. 4C–G). Corallite organization over the colony surface is the same as the typematerial throughout the whole collection. However, although corallites are generally flush with the coenosteum, in certain specimens they can be more sunken in certain parts of the corallum, typically towards the base of the digitations. At the corallite level, calice diameter, septal plan, and number of pali and denticles are consistent with the typeseries. In some specimens the denticles can be more visible ( Fig. 4J) than in others ( Fig. 4D). When this happens, the small corallites are more easily visible to the naked eye and attain a flower-like appearance ( Fig. 4J). The character showing the highest within and between specimens variability is the thickness of the innermost cycle of synapticulae ( Fig. 2). When the synapticulae connecting proximal ends of the septa are thicker the species typical pattern of septal fusion can be less easily visible ( Fig. 2D–F).   FIGURE 1Holotype of  Porites fontanesii  sp. nov.(MNHN-IK.2009-834) (A) In vivoimage of the whole colony; (B) The holotype; (C) Detail of a digitation of the holotype typical of the species; (D) Close up of C showing smooth colony surface, regular corallite arrangement and coenosteum; (E) Detail of D showing the corallite septal plan.  Field characteristics and identification.  Porites fontanesii  sp. nov.forms colonies ranging from a few centimeters to 50 cmin diameter and is found between 5 and 15 mdepth. The corallum base is usually encrusting and from it digitations of variable thickness and height develop ( Fig. 3A–D). In larger colonies branching can be observed. Digitations and branches tend to fan out ( Fig. 3A–D). Polyps are usually extended during the day ( Fig. 3D, F). When these are retracted the smooth surface of the corallum ( Fig 3E) and the corallites separated by the coenosteum ( Fig 3G) are visible. Colour ranges from grey or pale beige to light brown, and polyps are typically extended during the day. ( Fig. 3C–D).   Etymology.This species is named after Prof. Marcello Fontanesi, Magnifico Rettore of the University of Milano-Bicocca.   Distribution and frequency.  P. fontanesii  sp. nov.has been recorded from the southern Red Sea, the Gulf of Tadjoura, the Gulf of Aden and the north-western Indian Ocean ( Fig. 5). Southern Red Sea ( Yemen) Kamaran Island, Kutama, Tiqfash, Uqban, Al Badi, Gulf of Tadjoura ( Djibouti) Tadjoura, Obock, Musha Island, Northern Gulf of Aden ( Yemen) Aden, Balhaf, Bir Ali, Sikha Island, Burum, Al Mukallah, and from SocotraIsland. No additional records from published illustrations or museum specimens have been found so far.   Porites fontanesii  sp. nov.was most frequently observed in the YemenRed Sea islands ( Fig. 6) where it was observed in 88% of the sampled sites (n = 16). It was also frequently observed along the Gulf of Aden coast of Yemenat Aden (60%, n = 5), Balhaf-Bir Ali (72%, n = 32) and Burum-Mukallah (67%, n = 18). Finally, the species was recorded at 20% and 11% of the sites in Djibouti(n = 27) and Socotra(n = 15), respectively.   FIGURE 2SEM images of  Porites fontanesii  sp. nov.(A) Holotype (MNHN-IK.2009-834) corallite arrangement; The typical septal plan with a fused vetral triplet, a short dorsal septum, and five pali in a corallite of specimen UNIMIB MU027 (B), and in the holotype C); (D) Corallite arrangement at the base of specimen UNIMIB BAL151 (Fig. 4E–F); (E) A corallite in the same specimen with a typically thickened inner cycle of synapticulae connecting the proximal end of the septa resembling a hollow columella; (F) Detail of another corallite with a very thickened inner cycle of synapticulae. Larger arrows indicate the dorsal septum, smaller arrows the synapticulae connecting the dorsal septum to the lateral pairs.  Phylogenetic analysis.A total of 48 sequences were aligned and subjected to phylogenetic analysis. Overall, 572 positions (194 showing gaps) characterized the alignment after excluding two hypervariable and unaligneable regions (about 200 bp in total, situated at the beginning of ITS1 and at the end of ITS2). Among 85 variable sites, 69 were parsimony informative, while a GTR+G+I evolutionary models was selected as the most appropriate fro the data by AIC. The phylogenetic trees obtained according to the two different criteria showed concordant topologies ( Fig. 7). Two main clades were found, one relating to Central American  Poritesspecies, (subclades X, XI and XII sensuForsman et al.2009) and the other, a large, polytomic clade including both Atlantic and Pacific species (subclades IX, VIII, VII, VI, V, III, II, I sensuForsman et al.2009). In both cases, the internal relationships agreed with the phylogeny obtained by Forsman et al.(2009) from which the sequences were taken. Specimens of  Porites fontanesii  sp. nov.are found in a subclade basal to, and well divergent from, the second main clade. A mean value of 6.4% (± 1.3 s.d.) p-distance separates  P. fontanesii  sp. nov.from the other species of the genus. Internal divergence within  P. fontanesii  sp. nov.is one order of magnitude lower (0.5 % ± 0.3 s.d). Bayesian analysis performed with the software BEAST showed signals of convergence to the stationary distributions of parameters after 10.000.0 0 0 generations, since all ESS were largely> 200 and parameters distribution were smooth. The analysis was repeated three times obtaining the same inferences. An evolutionary pattern congruent with a molecular clock was not rejected (ucld.stdev = 0.3, 95% HPD 0.0–0.6) and a mean rate of 2.4 x10-2(95% HPD 1.3 x10-2–3.7 x10-2) subst/site*My was estimated. On these basis, the main divergence between  P. fontanesii  sp. nov.and the other polytomic clade is dated at 8.53 MYA (95% HPD 4.0–14.0 MYA), thus indicating a likely late Miocene origin of this species.