Tethocyathus virgatus (Alcock, 1902)

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

Tethocyathus virgatus (Alcock, 1902)

Fig. 5M, N

Trochocyathus (Thecocyathus) virgatus Alcock, 1902a: 98-99. - Alcock 1902c: 16-17, pl. 2, fig. 13.

Tethocyathus virgatus . - Cairns 1995: 65-66, pl. 16C-F. - Cairns and Zibrowius 1997: 114-115. - Cairns 1999a: 86. -Cairns 2004a: 286. - Cairns 2009: 9. - Kitahara et al. 2010a: 115. - Kitahara and Cairns 2021: 570-571, 573, figs 316, 317A-C.

Type locality.

Off Sulu Archipelago (HMS ‘Siboga’ stns. 96 and 105: South-east of Pearl Bank and 6°08'00"S, 121°19'00"E, respectively); 15-275 m ( Alcock 1902c).

Type material.

Two syntypes are deposited at the ZMA (Cairns 2004a).

Material examined.

SAMC_A073083 (1 specimen): 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_A073180 (2 specimens): Southern margin, 33 km from Mazeppa Bay / 24 km off Cwili Estuary, 32°45'47.88"S, 28°36'24.12"E; 240-250 m. USNM 91674 (1 specimen): Eastern margin, 32 km from Port Dunford / 37 km off Mlalazi Estuary, 29°05'10.79"S, 32 08'10.79"E; 95 m.

Description.

Corallum solitary, ceratoid to subcylindrical, and attached to substrate by a thick pedicel (PD:GCD = 0.2-0.7) that expands into a polycyclic encrusting base. Calice elliptical (GCD:LCD = 1.1-1.2), with a jagged calicular margin. Largest specimen examined (USNM 91674) 13.4 × 11.8 mm in CD, and 26.3 mm in H. Costae unequal, flat, granular, separated by shallow intercostal striae, and becoming less prominent towards base. Epitheca may be thick and penetrated by lenticular pores of acrothoracid barnacles, or thin with no incrustation. Corallum pigmented purple-black, that fades into a white colouration towards base.

Septa hexamerally arranged in five cycles, the last cycle being incomplete, according to the formula: S1> S2> S3 ≥ S4> S5 (<68 septa). Septa closely packed. S1-2 exsert, independent, thickest, and most swollen. Higher cycle septa (S3-4) progressively less exsert and less thick. S31/2 the width of S1-2. S4 dimorphic in size: those adjacent to S1 equal to or slightly wider than S3; and those adjacent to S2 usually less wide than S3. S5 same width as S4 adjacent to S1, if present. All septa have straight axial margins except for S3, which have slightly sinuous ones. Septal faces granular. Pali large, closely packed, and present before all septal cycles but last, forming a high paliform crown encircling a papillose columella composed of a group of closely-packed and low-profile rods.

Distribution.

Regional: Southern to eastern margin of South Africa, from Kei Mouth extending towards Port Dunford; 95-250 m. Elsewhere: Philippines; Indonesia ( Cairns and Zibrowius 1997); Vanuatu; Wallis and Futuna Islands ( Cairns 1999a); New Caledonia ( Kitahara and Cairns 2021); New Zealand ( Cairns 1995); Australia (Cairns 2004a); 95-1200 m.

Remarks.

Tethocyathus virgatus is distinguished from the other Recent congeners in having a pigmented CS1, S1-2 being the thickest septa, well-developed lamellar pali, and by attaining the largest corallum size. The examined specimens represent a new record for the region. The South African representative differs from the Australian in having septa of the fifth cycle (<68 septa) as compared with only four (48 septa), and in having S3 that bear a slightly sinuous rather than a straight axial margin. Nonetheless, all the other taxonomic features agree with what is known to be characteristic of the species.

Figures

Figure 5. A, F Stephanocyathus (Acinocyathus) explanans: A, C (USNM 62500, off Durban, 183 - 220 m) Calicular view B basal view C lateral view D, F (SAMC _ A 090144, off Port St Johns, 96 - 98 m) D calicular view E basal view F lateral view G, I Stephanocyathus (Odontocyathus) campaniformis (SAM _ H 3178, off Coffee Bay, 1420 m) G calicular view H basal view I lateral view J, L Stephanocyathus (Odontocyathus) nobilis (SAM _ H 1697, off Groot Berg Estuary, 1050 m) J calicular view K basal view L lateral view M, N Tethocyathus virgatus (SAMC _ A 073180, off Mazeppa Bay, 240 - 250 m) M calicular view N lateral view O, P Trochocyathus (Trochocyathus) sp. 1 (SAM _ H 1244, off East London, 59 m) O calicular view P lateral view. Scale bars: 10 mm.