Sphenotrochus (Sphenotrochus) imbricaticostatus Cairns in Cairns & Keller, 1993

Filander, Zoleka N., Kitahara, Marcelo V., Cairns, Stephen D., Sink, Kerry J. & Lombard, Amanda T., 2021, Azooxanthellate Scleractinia (Cnidaria, Anthozoa) from South Africa, ZooKeys 1066, pp. 1-198 : 1

Sphenotrochus (Sphenotrochus) imbricaticostatus Cairns in Cairns & Keller, 1993

Fig. 15M, N

Sphenotrochus aurantiacus . - Boshoff 1981: 38-39 (in part).

Sphenotrochus (Sphenotrochus) imbricaticostatus Cairns in Cairns & Keller, 1993: 258-259, fig. 9A-H.

Type locality.

Off Kosi Bay, South Africa (RV 'Meiring Naude’ stn. ZB27: 27°03'00"S 32°53'00"E); 44 m ( Cairns and Keller 1993).

Type material.

The holotype and eight paratypes are deposited at the NMNH, whilst one paratype is deposited at the SAM ( Cairns and Keller 1993).

Material examined.

SAMC_A090084 (1 specimen): Southern margin, 22 km from Cape Point / 4 km off Elsies Estuary, 34°09'59.99"S, 18°27'29.99"E; 24 m. SAMC_A090085 (in part: 12 specimen): Locality data unknown; 43 m. SAM_H3203 (in part: 2 specimens): Southern margin, 48 km from Kidds Beach / 14 km off Bira Estuary, 33°29'24.00"S, 27°22'59.99"E; 80 m. SAM_H4586 (2 paratypes): Eastern margin, 31 km south of Ponta Do Ouro / 32 km off Kosi-Kumpungwini (Sifungwe) Estuary, 24°48'00"S, 34°59.00"E; 42 m. USNM-91715 (holotype): Eastern margin, 23 km south of Ponta Do Ouro / 15 km off Kosi-Kumpungwini (Sifungwe) Estuary, 27°03'32.40"S, 32°52'59.99"E; 44 m. USNM-91717 (2 paratypes): Eastern margin, 38 km from Shaka’s Rock / 16 km off Zinkwasi Estuary, 29°21'00.00"S, 31°34'59.99"E; 57 m.

Description.

Corallum cuneiform, with highly compressed faces in lower corallum. Upper corallum highly flared, producing a rectangular-like side view. Base slightly rounded. Calice elliptical (GCD:LCD = 1.4-2.8). Largest specimen examined (USNM-91717) 3.7 × 2.5 in CD, and 6.7 mm in H. Costae smooth, flat, unequally in width, and ridged. In some specimens 12-14 costae overreach base and meet counterparts from opposite side. Pairs of C4 occur in each half-system adjacent to two S1 (32 costae), but S4 does not correspond to C4. Intercostal striae narrow, being slightly wider than costae. Corallum light brown.

Septa hexamerally arranged in three cycles according to the formula: S1-2> S3 (24 septa). S1-2 moderately exsert, equal in width, and extending 4/5 distance to columella with thickened and vertical axial margins. S3 equally exsert, but ¾ the width of S1-2. S3 axial margin narrow, straight to sinuous. Columella composed of a sharp-edged lamella that rises as high as septa. Columella and all septal faces covered by slender spines, giving them a rough appearance.

Distribution.

Regional: Southern and Eastern margin of South Africa, off Cape Point extending towards Kosi-Kumpungwini (Sifungwe) Estuary (23 km south of Ponta Do Ouro: Mozambique); 24-80 m. Elsewhere: south-eastern Mozambique ( Cairns and Keller 1993); 37-347 m.

Remarks.

Sphenotrochus (S.) imbricaticostatus differs from the two other South African species in the subgenus ( S. evexicostatus and S. aurantiacus ) by its compressed rectangular cuneiform corallum and wide, flat, imbricate costae, which alternates in width and imbricate with edges of adjacent costae ( Cairns and Keller 1993).

Figures

Figure 15. A, B Cyathotrochus pileus (SAMC _ A 087424, off Durban, 270 m) A calicular view B lateral view C, D Deltocyathoides orientalis (BIVa 2, locality unknown, 80) C calicular view D basal view E, F Deltocyathoides sentus (USNM 91551, off Shaka's Rock, 300 m) G, H Sphenotrochus (Eusthenotrochus) gilchristi (SAMC _ A 090086, off Cape Point, 24 m) G calicular view H lateral view I, J Sphenotrochus (Sphenotrochus) aurantiacus (SAM _ H 1416, off the Agulhas, 366 m) I calicular view J lateral view K, L Sphenotrochus (Sphenotrochus) evexicostatus (SAMC _ A 090085, locality data unknown, 43 m) K calicular view L lateral view M, N Sphenotrochus (Sphenotrochus) imbricaticostatus (USNM 91715 _ Holotype, off Kosi-Kumpungwini (Sifungwe) Estuary, 44 m) K calicular view L lateral view O, P Tropidocyathus lessonii (SAMC _ A 073218, off Kosi Bay Estuary, 74 m) O calicular view P lateral view. Scale bars: 10 mm (A-H, J-M, O-P); 2 mm (I, N).