Caulastraea, DANA, 1846: 197

Huang, Danwei, Benzoni, Francesca, Fukami, Hironobu, Knowlton, Nancy, Smith, Nathan D. & Budd, Ann F., 2014, Taxonomic classification of the reef coral families Merulinidae, Montastraeidae, and Diploastraeidae (Cnidaria: Anthozoa: Scleractinia), Zoological Journal of the Linnean Society 171 (2), pp. 277-355 : 300-302

GENUS CAULASTRAEA DANA, 1846: 197 ( FIG. 7 )

Synonyms

Astraeosmilia Ortmann, 1892: 664 (type species: Astraeosmilia connata Ortmann, 1892: 664 ; original designation, Ortmann, 1892: 664); Astreosmilia Veron, 1986: 595 (misspelling); Caulastrea Vaughan & Wells, 1943: 165 (misspelling); Dasyphyllia Milne Edwards & Haime, 1848a, vol. 27: 492 (type species: Dasyphyllia echinulata Milne Edwards & Haime, 1849a, vol. 11: 265, vol. 10, pl. 8: fig. 5; subsequent designation, Milne Edwards & Haime, 1849a, vol. 11: 265).

Type species

Caulastraea furcata Dana, 1846: 198 , pl. 9: figs 4, 4a–c; original designation, Dana, 1846: 198.

Original description

‘Segregato-gemmate, cespitose, with the stems and calicles subcylindrical. Coralla fragile, exterior excavate; lamellae unequally exsert, subentire, very numerous.’ ( Dana, 1846: 197).

Subsequent descriptions

Milne Edwards & Haime, 1857, vol. 2: 188; Dana, 1859: 22; Duncan, 1884: 77; Quelch, 1886: 74; Saville Kent, 1893: 160; Delage & Hérouard, 1901: 617; Matthai, 1928: 272; Yabe et al., 1936: 19; Vaughan & Wells, 1943: 165; Alloiteau, 1952: 616; Crossland, 1952: 139; Wells, 1956: F401; Nemenzo, 1959: 83; Wijsman-Best, 1972: 54; Chevalier, 1975: 101; Veron et al., 1977: 11; Scheer & Pillai, 1983: 103; Wood, 1983: 142; Veron, 1986: 446; Chevalier & Beauvais, 1987: 718; Veron & Hodgson, 1989: 269; Sheppard & Sheppard, 1991: 120; Budd & Johnson, 1999: 38; Veron, 2000, vol. 3: 91.

Diagnosis (apomorphies in italics)

Colonial, with intracalicular budding only. Corallites monomorphic and discrete (one to three centres); monticules absent. Phaceloid. Calice width medium (4–15 mm), with medium relief (3–6 mm). Septa in three cycles (24–36 septa). Free septa present but irregular. Septa spaced <six septa per 5 mm. Costosepta equal in relative thickness. Columellae trabecular and spongy (> three threads), <1/4 of calice width, and continuous amongst adjacent corallites. Paliform (uniaxial) and septal (multiaxial) lobes weak or moderate. Epitheca absent and endotheca abundant (vesicular) ( Fig. 7A, D, G ).

Tooth base at midcalice circular. Tooth tip at midcalice irregular; tip orientation perpendicular to septum. Tooth height low (<0.3 mm) and tooth spacing medium (0.3– 1 mm), with> six teeth per septum. Granules scattered on septal face; irregular in shape. Interarea palisade ( Fig. 7B, E, H ).

Walls formed by dominant paratheca; abortive septa absent. Thickening deposits fibrous. Costa centre clusters not distinct; medial lines strong. Septum centre clusters not distinct; medial lines strong. Transverse crosses present. Columella centres clustered ( Fig. 7C, F, I ).

Species included

1. Caulastraea furcata Dana, 1846: 198 , pl. 9: figs 4, 4a–c; syntype: USNM 80 (dry specimen; Fig. 7A ); syntypes: YPM IZ 1986 A, B, 4295 (three dry specimens); type locality: Fiji; phylogenetic data: molecular and morphology .

2. Caulastraea connata ( Ortmann, 1892: 664) ; holotype: lost (not found in MZS, PMJ, and ZMB); type locality: Dar es Salaam, Tanzania; phylogenetic data: none .

3. Caulastraea curvata Wijsman-Best, 1972: 56 , pl. 14: figs 3, 4; holotype: ZMA Coel. 5988 (dry specimen); paratypes: ZMA Coel. 5986, 5987, 5989 (three dry specimens); type locality: Baie de Prony , New Caledonia, 5 m depth; phylogenetic data: morphology only .

4. Caulastraea echinulata ( Milne Edwards & Haime, 1849a, vol. 11: 265, vol. 10, pl. 8: fig. 5); holotype: MNHN IK-2010-536 (dry specimen; Fig. 7D ); type locality: Singapore; phylogenetic data: molecular and morphology .

5. Caulastraea tumida Matthai, 1928: 275 , pl. 72: figs 5, 6; holotype: NHMUK 1928.6 .2.1 (dry specimen; Fig. 7G ); type locality: King’s Sound , Australia; phylogenetic data: molecular and morphology .

Taxonomic remarks

This genus was established by Dana (1846: 197) as part of the family Astraeidae Dana, 1846: 154 (see also Matthai, 1928: 272–273). He posited that Caulastraea is affiliated to Caryophyllia Lamarck, 1801: 370 , and Mussa Oken, 1815: 73 ( Dana, 1846: 198) , placing it in a subdivision comprising corals that are massive (‘glomerate’) or ‘calicularly branched’ ( Dana, 1846: 157). This united Caulastraea with a diverse group of genera, including Tridacophyllia de Blainville, 1830: 327 (= Pectinia de Blainville, 1825: 201 ), Astrea Lamarck, 1801: 371 , and Monticularia Lamarck, 1816: 248 (= Hydnophora Fischer von Waldheim, 1807: 295 ), all of which are currently in Merulinidae . This association persisted for almost a century before Pectiniidae Vaughan & Wells, 1943: 196 , was erected for Pectinia and Mycedium , amongst others, and Caulastraea transferred to Faviidae Gregory, 1900: 29 .

This genus is relatively well sampled, with only Caulastraea connata yet to be placed on the phylogeny. It was only recently that Veron (2000, vol. 3: 91) synonymized Astraeosmilia Ortmann, 1892: 664 , as Caulastraea Dana, 1846: 197 , resulting in the genus change of Astraeosmilia connata Ortmann, 1892: 664 .

Caulastraea is widely distributed on reefs of the Indo- Pacific, recorded as far east as the Pitcairn Islands in the Southern Hemisphere ( Glynn et al., 2007), but absent eastwards from Hawai’i in the north.

Morphological remarks

Molecular and morphological data support Caulastraea , Mycedium , Oulophyllia , and Pectinia as a monophyletic group (subclade XVII-D/E; Huang et al., 2011; Arrigoni et al., 2012), even though they differ in almost onethird of all macromorphological characters examined. Subcorallite characters, including DNA sequences, are therefore the main source of synapomorphies for this clade.

Caulastraea is a well-defined and well-supported genus (bootstrap support of 89 and decay index of 3). The phaceloid colony form (likelihood of 1.0 based on the Mk1 model), weak or moderate septal lobes (likelihood 1.0), and low tooth height (likelihood 1.0) are identified as synapomorphies that clearly distinguish it from the above closely related genera. It is the only Merulinidae genus with phaceloid attached colonies and possesses septal lobes that are not as well developed as those in Coelastrea , Goniastrea , and Trachyphyllia .

Figures

Figure 7. Caulastraea Dana, 1846, is phaceloid, with discrete corallites, equally thick costosepta spaced <six septa per 5 mm, weak/moderate paliform (uniaxial) and septal (multiaxial) lobes, and abundant (vesicular) endotheca. Septal teeth are low (<0.3 mm) with medium spacing (0.3–1 mm). Walls formed by dominant paratheca, with strong costal and septal medial lines, and transverse septal crosses. A–C, Caulastraea furcata Dana, 1846, type species of Caulastraea; macromorphology, syntype USNM 80, Fiji (A); micromorphology (scanning electron microscopy; B) and microstructure (transverse thin section; C), hypotype USNM 92394 (FA1035), Palau. D–F, Caulastraea echinulata (Milne Edwards & Haime, 1849a); macromorphology, holotype MNHN IK-2010-536, Singapore (D); micromorphology (E) and microstructure (F), hypotype RMNH 10752, Ambon, Indonesia. G–I, Caulastraea tumida Matthai, 1928; macromorphology, holotype NHMUK 1928.6.2.1, King’s Sound, Australia (G; photo by H. Taylor); micromorphology (H) and microstructure (I), hypotype RMNH 21563, north of Komodo, Indonesia.