Coeloseris Vaughan, 1918

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 : 152-153

Coeloseris Vaughan, 1918

(figs. 2M–O, 10)

Synonyms: Xishasiderastrea Zou, 1975 .

Type species: Coeloseris mayeri Vaughan, 1918 ; syntypes: usnm 45546, usnm 45547, usnm 45548, usnm 68296, usnm 85762, usnm M 546581 ( National Museum of Natural History , Smithsonian Institution, Washington, DC, USA); type locality: Murray Island ( Australia) .

Original description: ‘Corallum of massive growth-form. Calices polygonal, separated by simple, imperforate walls, which are secondarily thickened by vesicular endothecal dissepiments. Asexual reproduction by subequal fission. Septa imperforate, margins subentire, microscopically dentate. Synapticulae present, but rare; when present they are near the wall. No columella. This species is separable from the massive species of Pavona by the fewness of its synapticulae and the absence of columella.’ ( Vaughan, 1918: 139). Diagnosis: Colonial. Budding intracalicular and extracalicular. Corallites monomorphic and discrete. Fused walls. Calice of width small (<4 mm) and relief medium (3–6 mm). Septa in 3 cycles (24–36 septa). Free septa regular. Septal spacing narrow (<6 septa per 5 mm). Costosepta equal in relative thickness. Columellae absent. Paliform lobes absent. Endotheca abundant (vesicular). Septal faces delicately granular. Bundles of td fibers well delineated, perpendicular/slightly oblique to septal surface. Closely spaced rads. Polyp tentacles retracted at daytime, of shape simple. Species included: Coeloseris mayeri Vaughan, 1918 .

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via free access Taxonomic remarks: Coeloseris is a monotypic genus described from Murray Island ( Australia) by Vaughan (1918). The genus has been traditionally considered a member of Agariciidae given a superficial macromorphological resemblance with Pavona Lamarck, 1801 (see table 1; Matthai, 1928; Vaughan & Wells, 1943; Alloiteau, 1952; Wells, 1956; Veron & Pichon, 1980; Chevalier & Beauvais, 1987; Veron, 2000; Waheed et al., 2015a). Kitahara et al. (2012b) showed that Coeloseris differed from all extant agariciid genera as it lacks the main diagnostic micromorphological/microstructural characters of the family such as long menianes, scale-like organisation of tectura (thickening desposits outside the rapid accretion deposits of the wall), and beaded septa margins. Subsequently, a molecular study based on 18S rDNA suggested that C. mayeri was closely related to two species of Euphyllia and Galaxea and not related to the molecular lineage of Agariciidae (Arrigoni et al., 2017) . Here, we confirmed both previous molecular and morphological results and formally transferred Coeloseris to Euphylliidae .

Morphological remarks: Kitahara et al. (2012b) showed that Coeloseris lacks the main micromorphological/microstructural features that are typical of all extant members of Agariciidae . Indeed, like other euphylliid genera, Coeloseris shows delicately granular septal faces, with septal margin straight, composed of a sometimes separated but closely spaced rad region that, in transversely sectioned septa, result in not well delineated bundles of td fibers. Additionally, the present study indicates that an abundant endotheca, a character shared among all representatives of Euphylliidae , is present in Coeloseris while the two investigated agariciid species Gardineroseris planulata and Pavona cactus possess a sparse endotheca. From a macromorphological perspective, Coeloseris is easily distinguishable among euphylliids considering its growth form, small width of calice(<4 mm), and narrow septal spacing(<6 septa per 5 mm). Concerning the polyp morphology, Coeloseris is the only euphylliid genus displaying retracted tentacles at daytime.

Distribution: Coeloseris is widely distributed on the reefs of the central Indo-Pacific, occurring from the Andaman and Nicobar Islands and western Sumatra to as far east as Marshall Islands in the Northern Hemisphere and American Samoa in the Southern Hemisphere ( Pillai, 1983; Best et al., 1989; Jonker & Johan, 1999; Veron, 2000; Kenyon et al., 2010; Richards & Beger, 2013; Huang et al., 2015; Veron et al., 2015; DeVantier & Turak, 2017; Montgomery et al., 2019).Records from Kenya and South Africa are doubtful ( Lemmens, 1993; Riegl, 1993).