Fibulia punicea Payne, Samaai & Gibbons, 2025

Fibulia punicea Payne, Samaai & Gibbons sp. nov.

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Figure. 11 A–E View FIGURE 11 , Table 9 View TABLE 9

Material examined. Holotype. SAMC-A096921 (cross-reference TS 2472 & WSL-INV84(1)): Walters Shoal Seamount, Grid WSL042 , Station ALG10974 , coll. RV Algoa , (33°11.2’ S; 43°51.0’ E) - (33°11.2’ S; 43°50.7’ E), 28–34 m depth, 02 June 2014 GoogleMaps . Paratypes. SAMC-A096889 (cross-reference TS 2303 & WSL-INV55): Walters Shoal Seamount, Grid WSL022 , Station ALG10954 , coll. RV Algoa , (33°10.9’ S; 43°48.6’ E) - (33°11.2’ S; 43°50.2’ E), 72–170 m depth, 29 May 2014 GoogleMaps . SAMC-A096922 (cross-reference TS 2473 & WSL-INV84(2)) , SAMC-A096925 (cross-reference TS 2477 & WSL-INV84(6)): Walters Shoal Seamount, Grid WSL042 , Station ALG10974 , coll. RV Algoa , (33°11.2’ S; 43°51.0’ E) - (33°11.2’ S; 43°50.7’ E), 28–34 m depth, 02 June 2014 GoogleMaps . Additional material. TS 2487 ( WSL-INV84 (16)), TS 2497 ( WSL-INV84 (26)), TS 2510 ( WSL-INV84 (39)): Walters Shoal Seamount, Grid WSL042, Station ALG10974, coll. RV Algoa , (33°11.2’ S; 43°51.0’ E) - (33°11.2’ S; 43°50.7’ E), 28–34 m depth, 02 June 2014.

Type locality. Walters Shoal Seamount , south of Madagascar on the Madagascar Ridge , Western Indian Ocean ( Fig. 1 View FIGURE 1 ).

Description ( Fig. 11A View FIGURE 11 ). Thickly encrusting and amorphous form. Length 3.8 cm, width 3.0 cm and thickness 1.1 cm. Surface smooth and slippery, with ridges and randomly scattered oscules. Oscules, ~ 1–2 mm in diameter, often slightly indented. Texture rubbery, firm and dense. Specimen not compressible, nor easily torn. In one specimen (TS 2303), bright orange-red spherical eggs (~ 1 mm diameter) present. Colour in life dark red, light brown in preservative. Preservative becomes bright orange with time. Most specimens leave a red-brown exudate on tissue paper.

Skeleton ( Fig. 11B, C View FIGURE 11 ). Choanosome contains a multispicular reticulate skeleton, comprised of robust fibres arranged somewhat radially, cored with oxeas. Fibres ~100 µm thick, sinuous, running somewhat perpendicular to the surface, not differentiated into primary and secondary tracts. Oxeas and arcuate chelae scattered throughout. Fibres penetrate ectosome, expanding radially to form brushes. Ectosome contains erect, radial bouquets of oxeas that sometimes pierce the surface, <200 µm thick.

Spiculation ( Table 9 View TABLE 9 ). Megascleres. Oxeas hastate, smooth, straight or slightly curved: 319 (282–342) × 6 (4–8) µm, n = 20 ( Fig. 11D View FIGURE 11 ). Microscleres. Arcuate unguiferous isochelae: 14 (12–15) µm, n = 20 ( Fig. 11E View FIGURE 11 ).

Substratum, depth range and ecology. Seven specimens found on rocky substrata in two sleds, almost always in association with the same species of hydroid as epifauna. Depth range: 28– 170 m.

Etymology. The specific epithet punicea comes from Latin and means crimson or dark red.

Remarks. The present material conforms to the genus Fibulia Carter, 1886 as diagnosed having a plumose or confused choanosomal skeleton of multispicular tracts; microscleres arcuate or reduced isochelae and the presence of only a single size category of oxeas (Van Soest 2002).

The present material is compared with Fibulia ramosa ( Ridley & Dendy, 1886) and Fibulia ectofibrosa ( Lévi, 1963) from South Africa, Fibulia occiensis Rengaiyan, Kurian Palayil & Ingole, 2022 from the Central Indian Ocean Ridge, Fibulia myxillioides (Burton, 1932) from the Patagonian Shelf, and Fibulia novaezealandiae ( Brøndsted, 1924) from New Zealand. Note that F. ectofibrosa is currently assigned to the genus Isodictya in the World Porifera Database ( de Voogd et al., 2024), though Samaai & Gibbons (2005) considered it to belong to the genus Fibulia due to the presence of arcuate isochelae and a single size class of oxeas, rather than the palmate isochelae that are diagnostic of Isodictya .

The oxeas of Fibulia punicea Payne, Samaai & Gibbons sp. nov. are similar in average size to those of F. ramosa , F. ectofibrosa , F. myxillioides and F. novaezealandiae ( Table 9 View TABLE 9 ). The chelae are also similar in size range to those of F. novaezealandiae recorded from New Zealand ( Table 9 View TABLE 9 ).

Burton (1932) described Fibulia myxillioides as an erect, arborescent sponge with flattened anastomosing branches, or sub lamellate, with straight and smooth oxeas measuring 300 × 6 µm and arcuate isochelae of 30 µm ( Table 9 View TABLE 9 ). Fibulia ramosa is cylindrical and branched, possessing large (600 × 22 µm) fusiform oxeas, and medium size arcuate isochelae (20 µm). Fibulia occiensis is stalked and club-shaped with large oxeas (628 (483–700) × 19 (14.5–21) μm) and large, well-formed arcuate isochelae, 36 (30–40.5) μm ( Table 9 View TABLE 9 ). These species have different spicule sizes and also differ from F. punicea sp. nov. in terms of external morphology: F. punicea sp. nov. is thickly encrusting and dark red in colour.

Fibulia novaezealandiae , on the other hand, is encrusting and characterised by slender oxeas with long tapering points (350 × 6 µm). The arcuate isochelae are small (12–14 μm) and although similar in size range to F. punicea sp. nov. ( Table 9 View TABLE 9 ), they are strongly curved, with lateral teeth that stand vertically outward and are relatively long. Fibulia novaezealandiae also has its type locality in New Zealand and has not been recorded anywhere else ( de Voogd et al. 2024). It is highly unlikely that F. novaezealandiae would spread from New Zealand to the WIO or to an isolated shallow seamount on the Madagascar ridge, given that it has not been recorded from any other region in the Indo-Pacific ( de Voogd et al. 2024).

Fibulia ectofibrosa is massive, light yellow-grey sponge, with straight or slightly curved hastate oxeas with unequal ends, 300–375 × 10–12 μm [ Samaai & Gibbons 2005: 353 (318–382) × 14 (14) μm] and arcuate isochelae, 16 μm [ Samaai & Gibbons 2005:18 (18) μm]. Fibulia punicea sp. nov. is thickly encrusting and dark red in colour, with oxea ends that are equally hastate. The chelae’s shaft is roundly curved, and the frontal alae are sharply pointed but not well-formed (e.g. Fibulia occiensis ) and arranged in a group of three alae.