Flabellum (Flabellum) pavoninum Lesson, 1831

Fig. 11E-H

Flabellum pavoninum Lesson, 1831: 2. -Gardiner 1902: 123-125, pl. 4, figs 18-12. - Gardiner 1904: 98. -Gardiner and Waugh 1938: 174. -Zibrowius et al. 1975: 98-99, pl. 2, figs D-E. - Boshoff 1981: 35. -Cairns 1984: 20. - Zibrowius and Grygier 1985: 122.

Flabellum coalitum von Marenzeller, 1888: 48-49. - Cairns 1989a: 46, 50, fig. 24E, F, I-L.

Flabellum thourarsii . - Boshoff 1981: 34.

Flabellum sp. 6. - Cairns 1989a: 63, 67, fig. 2.

Flabellum (Flabellum) pavoninum . - Cairns 1989a: 46-50, figs 23G-L, fig. 24A-D. - Cairns and Keller 1993: 263-264. -Cairns 1994: 70-71, pl. 30, figs G-L, pl. 31, figs A-E. - Cairns and Zibrowius 1997: 150-151, figs A-D, G, H. - Cairns 1999a: 115-116, fig. 18G-I.

Type locality.

Off Sandwich Islands, Hawaiian Islands; no depth given (Cairns 1989b).

Type material.

Five syntypes are deposited at the MNHNP (Cairns 1989a).

Material examined.

ORI_DIIb1 (3 specimens): Locality data unknown; 27 m. ORI_DIIb4 (2 specimens): Locality data unknown. DEFF_NANSEN-INV17 (2 specimens): Eastern margin, 15 km from Scottburgh / 16 km off Mahlongwana Estuary, 30°18'00.00"S, 30°54'36.00"E; 226 m. DEFF_NANSEN-INV 51 (2 specimens): Eastern margin, 39 km from Shaka’s Rock / 37 km from Mdlotane Estuary, 29°34'47.99"S, 31°37'47.99"E; 130- 144 m. SAMC_A073053 (1 specimen): Eastern margin, 5 km from Cape Vidal / 16 km off St Lucia Estuary, 28°08'24.00"S, 32°36'24.11"E; 165 m. SAMC_A073063 (2 specimens): Eastern margin, 18 km from Cape Vidal / 19 km off Mfolozi Estuary, 28°17'30.11"S, 32°34'12.00"E; 100 m. SAMC_A073135 (2 specimens): Eastern margin, 19 km from Coffee Bay / 18 km off Mdumbi Estuary, 32°02'53.87"S, 29°19'41.87"E; 250- 280 m. SAMC_A073171 (1 specimen): Eastern margin, 48 km from Cape Vidal / 21 km from Mgobezeleni Estuary, 27°42'53.99"S, 32°40'54.11"E; 160 m. SAMC_A073213 (1 specimen): Eastern margin, 29 km from Durban / 14 km off Mbokodweni Estuary, 30°06'24.12"S, 31°00'47.88"E; 160- 170 m. SAMC_A073225 (2 specimens): Eastern margin, 34 km from Shaka’s Rock /off Tongati Estuary, 29°45'59.99"S, 31°25'59.99"E; 110- 130 m. SAMC_A090097 (5 specimens): Eastern margin, 34 km from Shaka’s Rock / off Tongati Estuary, 29°45'59.99"S, 31°25'59.99"E; 110- 130 m. SAMC_A090098 (4 specimens): Eastern margin, 46 km from Shaka’s Rock / 42 km off Mdlotane Estuary, 29°34'59.99"S, 31°41'59.99"E; 138 m. SAM_H1432 (1 specimen): Eastern margin, 2 km from Durban / 8 km off Umgeni Estuary, 29°51'59.99"S, 31°00'00.00"E; 101 m. SAM_H1477 (2 specimens): Eastern margin, 19 km from Shaka’s Rock / 3 km off Mdloti Estuary, 29°38'59.99"S, 31°07'59.99"E; 49 m. SAM_H3845 (8 specimens): Eastern margin, 34 km from Shaka’s Rock / off Tongati Estuary, 29°45'59.99"S, 31°25'59.99"E; 110- 130 m. SAM_H4582 (1 specimen): Eastern margin, 31 km from Shaka’s Rock / 33 km from Mhlali Estuary, 29°39'48.00"S, 31°30'05.99"E; 150 m. USNM 82134 (4 specimens): Eastern margin, 27 km from Durban / 22 km from Beachwood Mangroves, 29°48'00.00"S, 31°16'11.99"E; 232 m.

Imagery data.

BMNH 1950.1.11.30 (2 specimens): Locality data unknown. Mortensen 31 (5 specimens): Eastern margin, off Durban, 128 m. ZH10 (1 specimen): Eastern margin, 68 km from Cape Vidal/8 km off Mgobezeleni Estuary, 27°32'34.79"S, 32°43'33.59"E; 150 m.

Description.

Corallum flabellate, unattached, but bearing a narrow pedicel circular in profile. Calice compressed (GCD:LCD = 1.26-2.50), with smooth calicular margin. Largest specimen examined (DEFF_NANSEN-INV17) 48.3 × 19.3 mm in CD, 34.4 mm in H, and 1.3 mm in PD. Thecal faces planar but diverging in an angle between 50-70°. Thecal edges bear low and convex crest. Angle of thecal edge (excluding crest) between 93-138°. Corallum white or sometimes reddish brown.

Septa arranged in six cycles, last being incomplete, according to the formula: S1-3> S4> S5> S6 (≤ 141 septa). S1-3 equidistant, having moderately sinuous axial margin that join columella. Upper S1-3 distal margins notched. S4 ~ ¼ the size of S1-3, and have sinuous axial margin that sometimes joins columella. S5 ½ the width of S4 with sinuous to dentate axial margin. S6, if present, restricted to calicular margin. Septal faces bear spines perpendicular to septal margin. Fossa deep and narrow, containing a rudimentary columella.

Distribution.

Regional: Eastern margin of South Africa, off Coffee Bay extending towards Cape Vidal; 49-280 m. Elsewhere: Tanzania (Gardiner and Waugh 1938); Kenya (Cairns 1989b); Madagascar (Gardiner and Waugh 1938, Zibrowius et al. 1975); Maldives (Gardiner and Waugh 1938); Australia (Cairns 2004a); Vanuatu; Wallis and Futuna Islands (Cairns 1999a); New Caledonia (Kitahara and Cairns 2021); Philippines; Indonesia (Cairns and Zibrowius 1997); Hawaiian Islands; South China Sea; Japan (Cairns 1989a, 1999); 73-665 m.

Remarks.

Flabellum (F.) pavoninum is reported in two forms that display different GCD:LCD and thecal edge ratios. The GCD:LCD ratio range from 1.9-2.1 (as reported in the Flabellum coalitum form) to <2.4 (typical form), and the thecal edge from 74° ( Flabellum coalitum) to 139° (typical) (Cairns 1994). Intraspecific variation is detailed by Cairns (1989a, 1989b), who suggested that the South African representative is potentially a different species. This suspicion was later clarified by Cairns and Keller (1993) who noted that characteristics of both, the Japanese and South African representatives overlapped, therefore confirming the Indian Ocean species to be indeed F. pavoninum . Nonetheless, F. pavoninum may be mistaken with Pacific F. arcuatile Cairns, 1999, but can be distinguished by its lateral thecal edge.