Rhizopsammia compacta Sheppard & Sheppard, 1991

Fig. 10K, L

Rhizopsammia compacta Sheppard & Sheppard, 1991: 153, fig. 179. - Cairns and Keller 1993: 277, fig. 13B, E.

Balanophyllia bairdiana . - Boshoff 1981: 40.

Balanophyllia ponderosa . - Boshoff 1981: 41.

Type locality.

Off Musandam, Gulf of Oman; 35 m (Cairns and Keller 1993).

Type material.

The holotype is lodged at the BMNH (GBIF 2020).

Material examined.

ORI_EIa2 (2 specimens): Eastern margin, 14 km from Durban / 12 km off Mbokodweni Estuary, 29°58'00.00"S, 31°01'59.99"E; 49 m. ORI_EIa6 (40 specimens), ORICH_1 (2 specimens): Eastern margin, other locality data unknown. SAMC_A072979 (20 specimens): Southern margin, 21 km off Port Elizabeth / 16 km off Bakens River Estuary, 33°58'59.99"S, 25°46'59.99"E; 90 m. SAMC_A073033 (1 specimen): Eastern margin, 28 km south of Ponta Do Ouro / 17 km off Kosi Bay Estuary, 27°06'18.00"S, 32°52'00.12"E; 50 m. SAMC_A073041 (1 specimen): 24 km south of Ponta Do Ouro /16 off Kosi Bay Estuary, 27°04'00.00"S, 32°52'59.99"E; 69 m. SAMC_A073081 (6 specimens): Eastern margin, 27 km from Richards Bay / 40 km off Mlalazi Estuary, 29°00'24.11"S, 32°12'00.00"E; 152 m. SAMC_A073083 (6 specimens): Eastern margin, 28 km from Richards Bay / 40 km off Mlalazi Estuary, 29°00'54.00"S, 32°12'06.12"E; 215 m. SAMC_A073136 (1 specimen): Eastern margin, 39 km from Cape Vidal / 29 km off Mgobezeleni Estuary, 27°47'23.99"S, 32°38'53.87"E; 65- 70 m. SAMC_A073192 (3 specimens): Eastern margin, 69 km from Cape Vidal / 7 km off Mgobezeleni Estuary, 27°31'48.00"S, 32°42'47.99"E; 70 m. SAMC_A073199 (1 specimen, sub-sample of USNM 91800): Eastern margin, 17 km south of Ponta Do Ouro / 11 km off Kosi-Kumpungwini (Sifungwe) Estuary, 27°00'17.99"S, 32°55'18.12"E; 67 m. SAMC_A073204 (1 specimen): Eastern margin, 67 km from Cape Vidal / 7 km off Mgobezeleni Estuary, 27°32'48.12"S, 32°42'36.00"E; 68 m. SAMC_A073208 (1 specimen): Eastern margin, 16 km from St. Lucia Estuary / 17 km off Mfolozi Estuary, 28°17'30.11"S, 32°32'35.88"E; 50 m. SAMC_A073221 (1 specimen): Eastern margin, 68 km from Cape Vidal /5 off Mgobezeleni Estuary, 27°31'59.99"S, 32°42'00.00"E; 77 m. SAMC_A090105 (2 specimens): Locality data unknown. SAMC_A090112 (1 specimen): Southern margin, 11 km from Pringle Bay / 8 km off Buffels Oos Estuary, 34°16'29.99"S, 18°49'29.99"E; 14- 17 m. SAM_H1373 (5 specimens): Western margin, 14 km from Cape Town / 13 km off Diep Estuary, 33°57'31.20"S, 18°22'20.64"E; depth unknown. SAM_H1375 (1 specimen): Western margin, 14 km from Cape Town / 13 km off Diep Estuary, 33°57'31.20"S, 18°22'20.64"E; 44 m. SAM_H1380 (2 specimens): Southern margin, 16 km from Cape Point / 8 km off Elsies Estuary, 34°12'59.05"S, 18°27'57.32"E; 40 m. SAM_H1414 (1 specimen): Southern margin, 16 km from Cape Point / 8 km off Elsies Estuary, 34°12'59.05"S, 18°27'57.32"E; depth unknown. SAM_H1686 (6 specimens): Southern margin, 16 km from Cape Point/ 8 km off Elsies Estuary, 34°12'59.05"S, 18°27'57.32"E; depth unknown. SAM_H 2844 (1 specimen): Southern margin, 6 km from Kenton On Sea / 5 km off Boknes Estuary, 33°43'07.59"S, 26°37'37.95"E; 90 m. SAM_H4578 (1 specimen): Eastern margin, 6 km south of Ponta Do Ouro / 9 km off Kosi-Kumpungwini (Sifungwe) Estuary, 26°53'30.00"S, 32°55'36.00"E; 51 m. SAM_H4579 (2 specimens): Eastern margin, 42 km south of Ponta Do Ouro / 27 km off Kosi Bay Estuary, 27°13'30.00"S, 32°49'30.00"E; 74 m. USNM 91807 (2 specimens): Eastern margin, 38 km south of Ponta Do Ouro / 23 km off Kosi Bay Estuary, 27°11'17.99"S, 32°50'14.39"E; 78 m.

Description.

Colony irregularly shaped, composed of corallites interconnected by narrow stolons, or composed of small corallites budding from lower edge zone of larger corallites. Corallites ceratoid to cylindrical, bearing elliptical calices (GCD:LCD = 1.4-1.8), calicular margin lanceted. Largest colony examined (ORI_EIa6) consists of 20 corallites. Largest corallite (SAMC_A073041) 20.2 × 13.0 mm in CD, and 33.5 mm in H. If present, epitheca thin. Costae conspicuous throughout corallum, equal in width, covered with fine, pointed, and randomly arranged granules. Intercostal striae thin and deep. Corallum white.

Septa hexamerally arranged in five cycles according to the formula: S1 ≥ S2> S3> S5> S4, with occasional pairs of S6 in half-systems (≤ 112 septa). S1-2 both independent, most exsert, reaching columella with straight and smooth axial margins that become dentate deep in fossa. S3 slightly less to as exsert as S1-2, but having only ½ the width of S1-2, but otherwise similar in profile. Higher cycle septa (S4-5) progressively less exsert, if at all. S41/3 the width of S3, and have the least dentate lower axial margins. S5 ¾ wider than S4, merging towards S4 before joining columella as one septum. S5 axial margins dentate to laciniate. S6, if present, restricted to calicular margin. Septa commonly closely packed, with all septal faces being granular. Pali absent. Fossa of moderate depth, containing a spongy columella that fuses with axial margins of all septa except S4 (and S6 if present).

Distribution.

Regional: Western to eastern margin of South Africa, extending from off Cape Town towards Kosi-Kumpungwini (Sifungwe) Estuary (9 km south of Ponta Do Ouro: Mozambique); 40-215 m. Elsewhere: Gulf of Oman (Sheppard and Sheppard 1991; Cairns and Keller 1993); Mozambique (Cairns and Keller 1993); 35-110 m.

Remarks.

Our examined specimens agree with the redescription of Cairns and Keller (1993) of Rhizopsammia compacta . Although the lack of stolons may cause confusion with Balanophyllia diademata based on van der Horst’s (1927) description (and associated image), R. compacta can be distinguished by consistently having five complete septal cycles (occasionally with a pair of S6 = 6:6:12:24:48:16) as compared with five incomplete cycles of B. diademata (6:6:12:24:34). Rhizopsammia compacta may be distinguished from the other South African congeners by its relatively large adult corallum (20.0 mm CD), as compared with the medium-sized R. verrilli van der Horst, 1922 (8.0 mm) and the small R. annae (6.3 mm). The hexamerally arranged septa in six cycles (≤ 112 septa) may also assist with separating R. compacta from R. verrilli and R. annae, which both have septa hexamerally arranged in four cycles (48 septa).