Tubastraea Tubastraea diaphana (Dana, 1846)

Figs 10P, 11A

Dendrophyllia diaphana Dana, 1846: 389, pl. 27, fig. 3. - Vaughan 1918: 144-145, pl. 60, figs 2, 3.

Dendrophyllia aequiserialis Quelch, 1886: 147.

Dendrophyllia micranthus var. fruticosa Nemenzo, 1960: 17-18, pl. 9, fig. 1.

Tubastraea diaphana . -Scheer and Pillai 1983: 174, pl. 41, figs 1-4. - Cairns and Keller 1993: 284, pl. 13, fig. H. - Cairns and Zibrowius 1997: 196-197. - Cairns 1998: 409-410. - Cairns 2001: 29. -Cairns 2004a: 318.

Dendrophyllia sibogae van der Horst,1922: 56-57, pl. 8, figs 18, 19.

Type locality.

Singapore, depth unknown (Dana 1846).

Type material.

The holotype is deposited at the NMNH (Cairns 1994).

Material examined.

SAM_H5103 (1 specimen): Eastern margin, 59 km from Cape Vidal/ 9 km off Mgobezeleni Estuary, 27°36'38.45"S, 32°40'02.99"E; 59 m.

Description.

Colonies phaceloid, forming small bushy clusters of corallites. Branching achieved by extra-tentacular budding fairly closely at broad base (BD = 1.6). Corallites circular to slightly elliptical (GCD:LCD = 1.0-1.1), and ≤ 27.4 mm in H. Theca thin and porous. Costae well developed, particularly C1, which is the same-size as associated primary septa. Corallum white. Tissue pale orange in live specimen.

Septa hexamerally arranged in four cycles, last cycle being incomplete, according to the formula: S1> S2> S3-4 (48 septa). S1 exsert, with straight axial margins. S2 less than ¼ width of S1, and have dentate axial margins. S3-4 rudimentary, being wider deeper in fossa, and bearing dentate lower axial margins. Fossa of exceptional depth and spacious, containing a spongy columella.

Distribution.

Regional: Eastern margin of South Africa, off Aliwal shoal (Cairns and Keller 1993) and Cape Vidal; 9-59 m. Elsewhere: Zanzibar; Madagascar (Cairns and Keller 1993); Red Sea (Scheer and Pillai 1983); Australia (Cairns 2004a); Philippines (Cairns and Zibrowius 1997); Indonesia (van der Horst 1922); New Caledonia (Kitahara and Cairns 2021); Singapore (Dana 1946); 1-30 m

Remarks.

The examined specimen closely resembles Tubastraea diaphana (Dana, 1846) in that its corallum is phaceloid, a species reported by Cairns and Keller (1993) to occur in the Natal region. However, differences are observed in the tertiary and quaternaries septa: both being restricted to the calicular margin, tissue being pale orange, and in bearing a spongy columella (Fig. 10O). The specimen examined herein was collected at 23 m deeper depth than the maximum depth of Tubastraea diaphana .