Placotrochides scaphula 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

Placotrochides scaphula Alcock, 1902

Fig. 12C, D

Placotrochides scaphula Alcock, 1902c: 34, pl. 4, figs 32, 32A. -Wells 1936:124. - Zibrowius 1974d: 23. - Zibrowius 1980: 159. - Cairns 1989b: 78-79, pl. 40-41, figs 1 and A-E. -Cairns and Parker 1992: 48-49, figs 15H-I. - Cairns and Keller 1993: 272-273, pl. 12, figs D, G. -Cairns 1994: 79-80, pl. 34, figs F-H. - Cairns and Zibrowius 1997: 174. -Cairns and Kithara 2012: pl. 20, figs N-O. - Cairns 2016: 40, fig. 11C. - Li et al. 2017: 149. - Kitahara and Cairns 2021: 222, figs 110, 111A-C.

Type locality.

Off southeastern Celebes, Flores Sea, 462 m ( Cairns 1989b).

Type material.

The holotype is deposited at the ZMA ( Cairns 1989b).

Material examined.

USNM 91772 (3 specimens): Eastern margin, 28 km from Scottburgh/ 21 km off Mkomazi Estuary, 30°11'59.99"S, 32°01'00.00"E; 1360 m.

Imagery data.

MN_SM246 (4 specimens): Eastern margin, 39 km from Port St. Johns/32 km off Hluleka Estuary; 1660-1640 m.

Description.

Corallum compressed, cylindrical and robust. Thecal faces parallel. Calice elliptical (GCD:LCD = 1.2-1.3), with a smooth calicular margin. Largest specimen examined 6.4 × 5.0 mm in CD, and 3 mm in H. Costae wide and flat. Intercostal striae narrow. Reported to bear chevron-shape growth lines peaking at each costae and a large basal scar. However, examined specimens are eroded and these features are not visible. Corallum white.

Septa hexamerally arranged in four cycles according to the formula: S1-2 > S3 > S4 (42 septa). S1-2 have vertical and slightly sinuous axial margin. S3 dimorphic in development: when flanked by a pair of S4, S3 being ¼ smaller than S1-2, and bear smooth axial margin that fuse to columella. However, unflanked S3 being ¾ smaller than S1-2, and bear finely serrated axial margin. S4 rudimentary. All septa are non-exsert and widely spaced. Fossa deep and elongated, containing a trabecular columella.

Distribution.

Regional: Eastern margin of South Africa, off Scottburgh extending towards Port St. Johns; 930-1660 m. Elsewhere: Madagascar ( Cairns and Keller 1993); Australia (Cairns and Parker 1992); Japan (Cairns 1994); Philippines; Indonesia ( Alcock 1902a, 1902b; Cairns and Zibrowius 1997); New Caledonia ( Kitahara and Cairns 2021); 462-1628 m.

Remarks.

Apart from Placotrochides scaphula , there are four other Placotrochides known to date ( P. cylindrica Cairns, 2004, P. frustum Cairns, 1979, P. minuta Cairns, 2004, and P. yapensis Li, Yu-Rong & Xu, 2017) , of which P. scaphula most resembles P. minuta but can be distinguished by its larger corallum and higher number of septa at the same calicular diameter (Cairns 2004a). The large corallum size (< 12 mm) and septa arrangement are features P. scaphula shares with P. yapensis . These two species can be separated by the GCD:LCD ratio (1.4-2.1 in P. scaphula vs. 1.1-1.2 in P. yapensis ) and also by the number of septa (≤ 42 in P. scaphula vs. 48 in P. yapensis ). Placotrochides scaphula is well described by Cairns (1989b, 1994), and there are no new South African records subsequent to Cairns and Keller (1993), apart from the imagery records represented herein (MN_SM246).

Figures

Figure 12. A, B Javania insignis (SAMC _ A 090116, off Port Dunford, 85 m) A calicular view B lateral view C, D Placotrochides scaphula (USNM 91772, off Scottburgh, 1360 m) C calicular view D calicular view E, H Rhizotrochus typus E, F (SAMC _ A 090094, off Coffee Bay, 160 m) E calicular view F lateral view G, H (SCD 39 B, off Coffee Bay, 160 m) G calicular view H lateral view I, J Truncatoflabellum formosum (SAM _ H 1389, off Shaka's Rock, 183 m) I calicular view J lateral view K, L Truncatoflabellum gardineri (SAM _ H 3847, off Shaka's Rock, 138 m) K calicular view L lateral view M, N Truncatoflabellum inconstans (SAM _ H 1241, off Kei Mouth, 66 m) M calicular view N lateral view O, P Truncatoflabellum multispinosum (SAMC _ A 087450, locality data unknown) O calicular view P lateral view. Scale bars: 10 mm.