Gyrosmilia Milne Edwards & Haime, 1851

Arrigoni, Roberto, Stolarski, Jarosław, Terraneo, Tullia I., Hoeksema, Bert W., Berumen, Michael L., Payri, Claude, Montano, Simone & Benzoni, Francesca, 2023, Phylogenetics and taxonomy of the scleractinian coral family Euphylliidae, Contributions to Zoology 92 (2), pp. 130-171 : 157-159

Gyrosmilia Milne Edwards & Haime, 1851

(figs. 2P–R, 7, 11C–D)

Type species: Manicina interrupta Ehrenberg, 1834 ; holotype: zmb Cni749; type locality: Red Sea.

Original description: ‘polypier composé, se multipliant par fissiparité; polypiérites restant unis en séries, lesquelles sont soudées entre elles par leurs murailles; columelle nulle; les centres calicinaux distincts; cloisons minces, entiéres, glabres, serrées; l’endothéque n’occupant que les parties inférieures des loges.’ ( Milne Edwards & Haime, 1851: 55).

Diagnosis: Colonial. Budding intracalicular and extracalicular. Corallites monomorphic and uni- or multi serial. Fused walls. Calice of width medium (4–15 mm) and relief medium (3–6 mm). Septa in more than 4 cycles (Ẑ 48 septa). Free septa regular. Septal spacing medium (6–11 septa per 5 mm). Costosepta equal in relative thickness. Columella absent. Paliform lobes absent. Endotheca abundant (vesicular). Septal faces delicately granular. Bundles of td fibers not well delineated, perpendicular to septal surface. Closely spaced (zig-zag mid-septal zone) rads. Polyp tentacles partially/fully extended at daytime, of shape simple.

Species included: Gyrosmilia interrupta (Ehrenberg, 1834) .

Taxonomic remarks: Gyrosmilia was formally introduced by Milne Edwards & Haime (1851) to include a single species, namely G. interrupta . The monospecific genus can be easily distinguished by its unique morphology, forming meandroid small colonies with collines and absent columella ( Matthai, 1928; Scheer & Pillai, 1983; Sheppard & Sheppard, 1991). As such, the validity of Gyrosmilia has never been questioned by subsequent authors and, given a general resemblance to Euphyllia , the two genera have been traditionally placed together at the family level, with a few exceptions (see table 1; Milne Edwards & Haime, 1857; Vaughan & Wells, 1943; Alloiteau, 1952; Wells, 1956; Scheer & Pillai, 1983; Chevalier & Beauvais, 1987; Sheppard & Sheppard, 1991; Veron, 2000). Recently, Budd et al. (2012) transferred the genus to Euphylliidae . In this study, we showed that Gyrosmilia clustered within this family and was sister to Ctenella in both molecular and morphological phylogenetic trees.

Morphological remarks: As discussed in the morphological remarks section of Ctenella , the macromorphology of Gyrosmilia is similar to the one of Ctenella and the two genera differ by their columella that is absent in Gyrosmilia . Like in Euphyllia and Fimbriaphyllia , rad s in Ctenella correspond to a straight or zig-zag mid-septal (rad s) zone in transversely sectioned septa and bundles of td fibers are not well delineated, perpendicular to the septal surface. The septal surface with delicately granular textures distinguishes the genus from Euphyllia and Fimbriaphyllia .

Distribution: Gyrosmilia is restricted to the reefs of the Red Sea and south-western Indian Ocean, occurring in East Africa coast (including Tanzania, Kenya, Mozambique, and South Africa) to as far east as the Mascarene Archipelago ( Rosen, 1971; Faure, 1977; Rosen, 1979; Scheer & Pillai, 1983; Sheppard, 1987; Sheppard & Sheppard, 1991; Veron, 2000; Obura, 2012; Veron et al., 2015; DeVantier & Turak, 2017; Berumen et al., 2019).

(?) Montigyra Matthai, 1928

Type species: Montigyra kenti Matthai, 1928 ; holotype: bmnh 95.10.9.88; type locality: Lacepede Islands (Western Australia) .

Original description: ‘Massive, growth-size medium, calicinal surface convex. Valley continuous, comparatively wide and deep. Colline discontinuous, in the form of monticules varying in length. Septa evenly thin, upper half or two-thirds of principal ones more or less vertical, lower half or one-third broadening towards columella and appearing somewhat like paliform lobes. Septal margins finely dentate in upper half or two-thirds, teeth increasing in length in lower half or one-third, sides granular. Columella in the form of centres usually connected by 1–3 lamellae. This genus resembles Trachyphyllia and Callogyra in growth-size and in septal characters. Although walls are fused as in Callogyra , the collines thus formed are discontinuous, much thinner and not grooved. It differs from both genera in the columellar centres being usually connected by lamellae and not so well developed. Like Trachyphyllia and Callogyra , Montigyra is also an Indo-Pacific genus.’ ( Matthai, 1928: 255).

Species included: Montigyra kenti Matthai, 1928 .

Taxonomic remarks: Montigyra is a monotypic genus known from a single specimen from Western Australia ( Matthai, 1928). It has been historically considered a member of different families (see table 1; Matthai, 1928; Wells, 1956; Chevalier & Beauvais, 1987; Veron, 2000). Recently, Budd et al. (2012) transferred the genus to Euphylliidae as being closely related to Gyrosmilia and this taxonomic action is herein maintained since we did not investigate the genus.

Distribution: Montigyra is known only from Lacepede Islands, Western Australia ( Matthai, 1928; Veron, 2000).

(?) Simplastrea Umbgrove, 1939

Type species: Simplastrea vesicularis Umbgrove, 1939 ; holotype: rmnh.coel9362 (Naturalis Biodiversity Center, Leiden, the Netherlands – formerly Rijksmuseum van Natuurlijke Historie); type locality: Onrust Island , Bay of Jakarta ( Indonesia).

Original description: ‘Corallites separated by a vesicular coenenchyma. Septa extending outside the calicular walls to meet either a septocosta of an adjacent corallite or a lamen of the choenenchyma. Corallite walls formed by vertical lamina of the coenenchyma and of a discontinuous broken appearance. Septal edges subentire. Columella trabecular. Dissepimenta present, no synapticulae. The coral seems close to Physogyra from which it may be distinguished especially by the occurence of a kind of pseudo-corallite walls.’ ( Umbgrove, 1939: 24).

Species included: Simplastrea vesicularis Umbgrove, 1939 .

Taxonomic remarks: Simplastrea is a monotypic genus described on the basis of a single likely fossil specimen from Indonesia ( Umbgrove, 1939). It was originally included in Eusmiliidae Milne Edwards & Haime, 1857 and, subsequently, transferred to other families in conjunction with Galaxea , to whom it morphologically resembles the most (see Table 1 ; Vaughan & Wells, 1943; Alloiteau, 1952; Wells, 1956; Veron & Pichon, 1980; Veron, 2000). Lastly, Budd et al. (2012) considered Galaxea and Simplastrea as genera belonging to Euphylliidae based on molecular evidence available for the former one. In this study, Simplastrea was not collected and its placement within Euphylliidae proposed by Budd et al. (2012) is hence maintained.

Distribution: Simplastrea is known only from the reefs of Indonesia and Papua New Guinea ( Umbgrove, 1939; Veron, 2000). The species was described from Onrust Island in Jakarta Bay ( Umbgrove, 1939) but has not been reported from this locality since then (van der Meij et al., 2010). The reef conditions around this island, which is located nearshore and close to Jakarta, have degraded in the last decades (Cleary et al., 2006, 2008, 2014).