Dendrophyllia dilatata van der Horst, 1927

Fig. 8M, N

Dendrophyllia dilatata van der Horst, 1927: 2-3, figs 2-4. - Zibrowius and Gili 1990: 44. - Cairns and Keller 1993: 278-279. -Cairns 1994: 89. - Cairns 2001: 34.

Type locality.

Off Richards Bay, South Africa (RV 'Pieter Faure’ stn. 12103: ca. 28°47'00.0"S, 32°20'00.0"E); 97 m (van der Horst 1927).

Type material.

The holotype is deposited at the ZMA (Creuwels 2020).

Material examined.

SAMC_A073016 (2 specimens): Eastern margin, 31 km from Richards Bay / 46 km Mlalazi Estuary, 29°00'54.00"S, 32°15'35.99"E; 500 m. SAMC_A073068 (1 specimen): Eastern margin, 47 km from Cape Vidal / 28 km off Mgobezeleni Estuary, 27°43'11.99"S, 32°40'36.11"E; 100 m.

Description.

Colony unattached and arborescent, with sympodial branching formed by extra-tentacular budding. Corallum ceratoid to sub-cylindrical, straight to slightly curved. Largest specimen examined (SAMC_A073016) 105.5 mm in H, with ≤ 30 corallites. Calice elliptical (GCD:LCD = 0.9-1.2), with serrated calicular margin. Epitheca absent. Costae well developed at upper corallum, rounded, granular, non-perforate, and separated by thin, porous, intercostal striae. Corallum white.

Septa hexamerally arranged in four complete cycles according to the formula: S1-2> S4> S3 (48 septa). S1-2 both independent, reaching the columella with straight axial margins, which may also be finely serrated. S1 most exsert, followed by S2. S3 ~ 1/3 the width of S2. S4 slightly wider than flanked S3, arranged in Pourtalès plan: in each half-system a pair of S4 fuses before S3 with jaggedly dentate axial margins. Fossa deep, containing a large, and slightly raised spongy columella.

Distribution.

Regional: Eastern margin of South Africa, off Richards Bay towards Cape Vidal; 97-500 m. Elsewhere: Mozambique (Cairns and Keller 1993); 97-132 m.

Remarks.

Dendrophyllia dilatata resembles Dendrophyllia sp. 1 in its growth form: i.e., large, dendroid colonies with fairly regular sympodial arranged corallites (Cairns 1994). However, it can be distinguished by having four cycles of septa as compared with three ( Dendrophyllia sp. 1), a well-developed Pourtalès plan development (poorly developed in Dendrophyllia sp. 1), lacking P2 which is present in Dendrophyllia sp. 1, and a larger columella (smaller in Dendrophyllia sp. 1).