Fungiacyathus (Bathyactis) sibogae (Alcock, 1902a)

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

Fungiacyathus (Bathyactis) sibogae (Alcock, 1902a)

Fig. 13I-L

Bathyactis sibogae Alcock, 1902a: 108.

Bathyactis symmetrica . -von Marenzeller 1904a: 312-313, pl. 18, fig. 25. - Gardiner and Waugh 1939: 231.

Bathyactis stabilis Gardiner & Waugh, 1939: 231-232, figs 1, 2.

Fungiacyathus (Bathyactis) sibogae . - Cairns 1989b: 10-11, pl. 3, figs D-K, pl. 4, figs A-C. - Cairns and Keller 1993: 218, 230. - Cairns and Zibrowius 1997: 70.

Type locality.

Ceram Sea, Indonesia (HMS ‘Siboga’ stn. 175: 2°37.7'00"S, 130°33.4'00"E); 1914 m (Alcock, 1902a).

Type material.

The paralectotype is deposited at the ZMA ( Cairns and Zibrowius 1997).

Material examined.

None.

Imagery data.

SAM_H1403 (1 specimen): Eastern margin, off Durban harbour, 805 m. SAM_H1688 (in part: 2 specimens): eastern margin, 51 km south of Ponta Do Ouro/40 km off Mgobezeleni Estuary, 27°18'42.00"S, 32°57'47.99"E; 840 m. SAM_H1689 (in part: 1 specimen): eastern margin, 44 km south of Ponta Do Ouro/35 km off Kosi Bay Estuary, 27°14'47.99"S, 32°57'59.99"E; 900 m. SAM_H1697 (2 specimens): eastern margin, 58 km south of Ponta Do Ouro/46 km off Mgobezeleni Estuary, 27°21'18.00"S, 33°03'53.99"E; 1050 m.

Description.

Corallum discoidal, with a flat to slightly convex base, reaching ≤ 14.5 mm in CD. Costae ridged, serrate, and narrow. C1-2 ridged from epicentre of base to calicular margin, and C3-4 ridged only near calicular margin. Costae correspond with septa in width, with C1-2 equal in width and C3-4 becoming progressively narrower. Intercostal spaces moderately deep and granulated. Corallum white.

Septa hexamerally arranged in four cycles according to the formula: S1 > S2 > S3 > S4 (48 septa). S1 highly exsert and extend to columella. S1 appear to be independent, but are connected to adjacent S4 by five or six synapticular bars, which gradually increase in size near calicular margin. S2 slightly less exsert and less wide than S1. S2 bear 4-6 trabecular spines, of which the third and fourth are the tallest and often curved towards columella. S3 equally exsert and slightly wider than S2, bearing 4-7 trabecular spines, of which the fourth to sixth are elongated and inclined towards columella. S4 least exsert and smaller septa, but have nine or ten trabecular spines. S2-4 fuse in a typical fungiacyathid fashion, forming porous and rudimentary canopies. All septa, except S4, have septal lobe occurring peripheral to spines. Septal faces planar, covered with serrated ridges, which are covered by broad and well-spaced teeth, thus giving a dentated appearance. Marginal shelf absent. Columella papillose.

Distribution.

Regional: Eastern margin of South Africa, off Durban towards Kosi Bay Estuary (35 km south of Ponta Do Ouro: Mozambique); 805-1050 m. Elsewhere: Mozambique ( Cairns and Keller 1993); Tanzania (von Marenzeller 1904a); Kenya; Madagascar; Gulf of Oman ( Gardiner and Waugh 1939); Indonesia ( Alcock 1902a; Cairns 1989b; Cairns and Zibrowius 1997); 463-1914 m.

Remarks.

Fungiacyathus (B.) sibogae differs from F. hydra in its septal faces being dentate, and its papillose columella. Although the above records are based on images of specimens that we were unable to track in the South African Museum collection, the diagnostic features are visible and as such specimens fit the description provided in Cairns (1989b).

Figures

Figure 13. A, B Truncatoflabellum pusillum (SAM _ H 2839, off Cape Padrone, 37 m) A calicular view B lateral view C, D Truncatoflabellum zuluense (SAMC _ A 090096, off Cape Vidal, 85 m) C calicular view D lateral view E, F Truncatoflabellum sp (SAMC _ A 073161, off Port St. Johns, 140 - 145 m) E calicular view F lateral view G, H Fungiacyathus (Bathyactis) hydra (USNM 86869, off Alexandra Bay, 882 m) G calicular view H basal view I, L Fungiacyathus (Bathyactis) sibogae (SAM _ H 1697, off Mgobezeleni Estuary, 1050 m) I calicular view J basal view K calicular view L basal view M, N Fungiacyathus (Fungiacyathus) sp. (SAM _ H 1431, off Durban, 99 m) M calicular view N basal view O, P Guynia annulata (USNM 77201, off Port St. Johns, 138 m) O calicular view P lateral view. Scale bars: 10 mm (A-N); 2 mm (O, P).