Euphyllia Dana, 1846

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 : 150-152

Euphyllia Dana, 1846

(figs. 1A–F, 8)

Synonyms: Euphyllia (Euphyllia) Dana, 1846 ;

Leptosmilia Milne Edwards & Haime, 1848 ; Downloaded from Brill.com 08/29/2023 05:29:52PM via free access

Plocophyllia Reuss, 1868 ; Euphyllia (Euphyllia) Veron & Pichon, 1980 .

Type species: Caryophyllia glabrescens Chamisso & Eysenhardt, 1821 ; holotype: not traced (illustrated in Chamisso & Eysenhardt, 1821: plate xxxiii, figs. 1a, 1b); type locality: Ratak Chain ( Marshall Islands) .

Original description: ‘Quite simple, or segregato-gemmate, rarely free: zoophytes hemispherical. Tentacles oblong, subequal. Coralla having the calices subturbinate, either circular or much compressed, sometimes meandering; lamellae nearly or quite entire; cell very narrow at bottom.’ (Dana, 1846: 157).

Diagnosis: Colonial. Budding intracalicular and extracalicular. Corallites monomorphic and discrete. Colonies phaceloid. Calice of relief high (> 6 mm) and width large (> 15 mm). Septa in Ẑ 4 cycles (Ẑ 48 septa). Free septa regular. Septa spacing wide (> 11 septa per 5 mm). Costosepta unequal in relative thickness. Columellae reduced to inner septa margin processes, with size small relative to calice width (<1/4), with linkage absent. Paliform lobes absent. Endotheca abundant (vesicular). Septal faces with shingles absent or small-sized. Bundles of td fibers typically perpendicular to septal faces or not well delineated. Closely spaced (zig-zag mid-septal zone) rads. Polyp tentacles fully extended at daytime, of shape simple.

Species included: Euphyllia glabrescens (Chamisso & Eysenhardt, 1821) ; Euphyllia baliensis Turak, Devantier & Erdman, 2012 ; Euphyllia cristata Chevalier, 1971 ; Euphyllia paraglabrescens Veron, 1990 .

Taxonomic remarks: Dana (1846) originally introduced Euphyllia to include a total of 13 species. For detailed explanations on the determination of E. glabrescens as the type species of the genus see Vaughan (1918: 81) and Matthai (1928: 173). As with other euphylliid genera, Euphyllia has been historically transferred to several families based on skeletal macromorphology (see table 1; Milne Edwards & Haime, 1857; Vaughan & Wells, 1943; Alloiteau, 1952; Wells, 1956; Veron & Pichon, 1980; Chevalier & Beauvais, 1987; Veron, 2000). This historical taxonomic uncertainty was initially solved by a first comprehensive molecular phylogenetic tree of scleractinian corals showing that Euphyllia clustered within clade V sensu Fukami et al. (2008), together with Ctenella and Galaxea (Fukami et al., 2008) . On the basis of these molecular results, Budd et al. (2012) re-organised the family Euphylliidae to include the members of clade V sensu Fukami et al. (2008). Subsequently, Luzon et al. (2017, 2018) found that representatives of Euphyllia were split in two main molecular lineages (see also Fukami et al., 2008; Lin et al., 2011; Akmal et al., 2017). Using a combination of molecular, morphological (skeleton and polyp morphology), and reproductive data, Luzon et al. (2017) revised Euphyllia to consist of four species, namely E. glabrescens , E. baliensis , E. cristata , and E. paraglabrescens , and moved the other five species of Euphyllia into Fimbriaphyllia . Our molecular and morphological results confirmed and strongly supported the study by Luzon et al. (2017, 2018). Although we were not able to trace the holotype of E. glabrescens , the type species of Euphyllia , we did not designate a neotype because we did not perform a comprehensive search in all relevant museums and we cannot exclude that the holotype is deposited somewhere. Despite much of the Chamisso’s collection is deposited in the Museum für Naturkunde (zmb, Berlin, Germany), the type of the species could not be located there. To identify our specimens, we referred to the original illustration of E. glabrescens in Chamisso & Eysenhardt (1821: pl. xxxiii, figs. 1a, 1b).

Morphological remarks: Within Euphylliidae , the genus shares several macromorphological characters with Fimbriaphyllia , for example a phaceloid Downloaded from Brill.com 08/29/2023 05:29:52 PM via free access coenosteum, large calice relief (> 15 mm), and wide septa spacing (> 11 septa per 5 mm). Nevertheless, the two genera can be told apart by their columella, which is reduced to inner septa margin processes, with a small size relative to calice width (<1/4), and with absent linkage in Euphyllia . Micromorphologically, while Euphyllia exhibits closely spaced (zig-zag mid-septal zone) rads similar to Fimbriaphyllia and Gyrosmilia , it is distinguished from these two genera by having septal faces with shingles absent or small-sized. Finally, Euphyllia and Fimbriaphyllia are the only euphylliids having polyps always fully extended at daytime but their polyp shapes easily distinguish the two genera, as also described and discussed in detail by Luzon et al. (2017, 2018). Euphyllia displays a simple polyp shape while representatives of Fimbriaphyllia have tentacles with complex shapes (see also Veron, 2000).

Distribution: Euphyllia is widely distributed on the reefs of the Indian and Pacific Oceans, occurring from the Arabian Sea and East Africa as far east as Marshall Islands in the Northern Hemisphere and Tonga and American Samoa in the Southern Hemisphere ( Lamberts, 1983; Best et al., 1989; Sheppard & Sheppard, 1991; Veron, 2000; Obura, 2012; Richards & Beger, 2013; Huang et al., 2015; Veron et al., 2015; Waheed et al., 2015b; DeVantier & Turak, 2017; Montgomery et al., 2019). Records of E. glabrescens from the Red Sea (Berumen et al., 2019) remain uncertain and mainly based on accounts of the skeleton macro-morphology devoid of tentacles images or detailed description. It is indeed possible that records of Euphyllia in the Red Sea actually referred to Fimbriaphyllia . For example, the historical record by Scheer & Pillai (1983: Plate 37, Fig. 3 ) is based on material showing the same corallum and septa morphology as the material of Fimbriaphyllia paradivisa we collected and examined from the south Red Sea (fig. 1M‒O). Conversely, records of Red Sea Fimbriaphyllia , especially from mesophotic depths, are numerous and well-illustrated showing the typical complex morphology of the extended tentacles in this genus (e.g., Eyal et al., 2016: Fig. 2 ), albeit still mostly classified as Euphyllia (e.g., Rinsky et al., 2022).

Figures

figure 2 In situ (a, d, g, j, m, p, close-up of the tentacles in the inset) and skeleton (b–c, e–f, h–i, k–l, n–o, q–r) images of the taxa examined in this paper.Galaxea astreata: (a, c) unimib–TO MY001,Ile Blanche, Mayotte Island, (b) unimib–TO DJ042, Oblal, Djibouti, (c) unimib–TO DJ325, Ghoubet el Kareb, Djibouti.Galaxea acrhelia: (d–f) unimib PFB166, Masas Island, Madang, Papua New Guinea.Galaxea horrescens: (g–h) ird HS4121, Chesterfield Islands, New Caledonia, (i) unimib pfb478, Usien Island, Kavieng, Papua New Guinea.Galaxea paucisepta, Prony Bay, New Caledonia:(j–l) ird HS2895. Coeloseris mayeri: (m, o) unimib pfb127, Masas Island, Madang, Papua New Guinea, (n) ird HS1768, Cap Goulvain, New Caledonia. Gyrosmilia interrupta: (p–r) kaust SA0001, Al Lith, Saudi Arabia.

figure 3 Bayesian inference molecular phylogeny reconstruction of Euphylliidae based on three mitochondrial loci (coi, 12S rRNA,and 16S rRNA). Numbers at nodes indicate Bayesian posterior probabilities (Ẑ0.70), maximum likelihood bootstrap supports (Ẑ70), and maximum parsimony supports (Ẑ70), respectively. Colours and clade names refer to Luzon et al. (2017, 2018).