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Homophyllia

Brüggemann, 1877, p. 310

Type Species

Caryophyllia australis Milne Edwards and Haime, 1849, p. 239, pl. 8, fig. 1; Original Designation Brüggemann, 1877, p. 310

Type Specimen: Syntype; NHMUK 40.11.30.70, 79; Verified; Dry Preserved

Type Locality: "Habite le port Lincoln (Australie)", (Recent)

Classification

Diagnosis

Colonial, but may be solitary in Homophyllia australis; colonies submassive or massive. Budding intracalicular, and may also be extracalicular. Corallites typically monomorphic; discrete. Monticules absent. Walls fused. Calice width large (> 15 mm), with high relief (> 6 mm). Costosepta mostly confluent. Septa in ≥ four cycles (≥ 48 septa). Free septa irregular. Septa spaced 6–11 septa per 5 mm. Costosepta unequal in relative thickness. Columellae trabecular and spongy (> three threads), < 1/4 of calice width, and discontinuous among adjacent corallites with lamellar linkage. Internal lobes usually absent. Epitheca well developed. Endotheca low-moderate (tabular). Tooth base at midcalice elliptical-parallel. Tooth tip orientation parallel. Teeth tall (> 0.6 mm); widely spaced (> 1 mm), with > six teeth per septum. Tooth shape equal between first and third order septa. Tooth size equal between wall and septum, but the teeth at midcalice may be larger than those at the columellar end of the septum. Granules distributed uniformly on septal face; weak (rounded). Interarea smooth. Walls formed by dominant paratheca and partial septotheca. Thickening deposits in concentric rings with extensive stereome. Costa centre clusters strong; > 0.6 mm between clusters; medial lines weak. Septum centre clusters weak; > 0.5 mm between clusters; medial lines weak.

Description

'Coral neatly turbinate, with a narrow, somewhat expanded base. Outside of wall covered almost to the edge with a thin closely adherent epitheca, through which the costæ are distinctly perceptible. Costæ crowded, perfectly equal, prominent, minutely denticulate. Calicle circular, deep. Edges of septa with crowded, narrow, subequal teeth. Columella very small, rounded in outline, coarsely trabecular.' (Brüggemann, 1877: 310)

Comparisons

The Homophyllia clade comprising two species is moderately supported on the morphology tree with a bootstrap value of 63, as well as the synapomorphies of tall teeth (> 0.6 mm) (likelihood of 0.99 based on the Mk1 model) and granules distributed uniformly on the septal face (likelihood 1.00). It is the sister genus to Micromussa based on molecular characters, but forms a paraphyletic group with Micromussa and Australophyllia on the basis of morphological traits. Homophyllia is easily distinguished from these closely-related genera by its larger and deeper calice, greater tooth height and spacing, and uniformly-distributed granules. Homophyllia australis may be unique among congeneric and closely-related allogeneric species in being predominantly solitary, but polystomatous specimens have been observed and collected (Veron, 1986, 2000; Arrigoni et al., 2016a), including even one of its two syntypes, NHMUK 1840.11.30.79. In these cases, corallites may no longer be considered monomorphic as diagnosed for the genus. We also note that several coralla of H. bowerbanki contain a central corallite that is slightly larger than usual.

Remarks

Homophyllia was established by Brüggemann (1877: 310) to contain Caryophyllia australis Milne Edwards and Haime, 1849a, vol. 11: 239, the type and only one of two species to have been assigned to the genus until Arrigoni et al. (2016a) transferred into it a species previously in Acanthastrea. Heterocyathus incrustans (Dennant, 1906: 161), a junior synonym of the facultatively zooxanthellate Heterocyathus sulcatus (Verrill, 1866: 48), was provisionally placed in Homophyllia when it was first described (Cairns, 2009). The validity of Homophyllia had been undermined for a considerable part of its taxonomic history. Matthai (1928) and Wells (1937) thought that it is an early monocentric stage of Lobophyllia and therefore synonymised Homophyllia under the latter. Vaughan and Wells (1943) did not question this scheme but Wells (1956) recognised it as a genus distinct from Lobophyllia. Based on the similarity between Caryophyllia australis Milne Edwards and Haime, 1849a, vol. 11: 239, and Scolymia vitiensis Brüggemann, 1877: 304, Veron and Pichon (1980) placed both of them in Scolymia Haime, 1852: 279. Homophyllia and Parascolymia Wells, 1964: 379, respectively contained these species, and were thus synonymised under Scolymia. The authors were also not convinced that these two species were distinct, emphasising that 'H. australis and Scolymia (= Parascolymia) vitiensis may be the same species, the former being a cold water ecomorph or geographic subspecies of the latter' (Veron and Pichon, 1980: 244). Nevertheless, they have remained as valid species to date, and were considered as the only Indo-Pacific members of Scolymia (Wood, 1983; Veron, 1986, 2000), whose type species Madrepora lacera Pallas, 1766: 298 (see Vaughan, 1901: 6), is an Atlantic species. The deep divergence between the Atlantic (clade XXI sensu Fukami et al., 2008) and Indo-Pacific corals (Fukami et al., 2004b, 2008) revealed by genetic data meant that the two Indo-Pacific members of Scolymia had to be redistributed into Homophyllia and Parascolymia (Budd et al., 2012). A more recent molecular analysis indicated that Acanthastraea bowerbanki Milne Edwards and Haime, 1857, vol. 2: 503, and A. hillae Wells, 1955: 15, are indistinguishable and form a sister group to Homophyllia australis, so A. hillae became a junior synonym of Homophyllia bowerbanki (Arrigoni et al., 2016a). Our analyses lend support to this classification. Homophyllia is present on the reefs of western Indian Ocean (Sheppard and Sheppard, 1991) and central Indo-Pacific, to as far east as the Marshall Islands in the Northern Hemisphere (Veron, 2000) and Austral Islands in the Southern Hemisphere (Glynn et al., 2007).

Distribution

  • Indian Ocean; Recent
  • Western Pacific; Recent
  • Central Pacific; Recent

This page has been in preparation since 19-Jul-2010 03:43

This version was contributed by Danwei Huang on 29-Jan-2016 13:40.

Page authors are: Ann Budd Danwei Huang. Please contact the editor if you would like to contribute to the diagnosis of this taxon.

The editor is: Ann Budd

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