Agelas kellyae Payne, Samaai & Gibbons, 2025

Agelas kellyae Payne, Samaai & Gibbons sp. nov.

urn:lsid:zoobank.org:act:C0DAE477-A890-47AC-8793-DAE26685D270

Figure 6A–F View FIGURE 6 , Table 4 View TABLE 4

Material examined. Holotype. SAMC-A096894 (cross-reference TS 2313 & WSL-INV48): 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 . Paratypes. SAMC-A096891 (cross-reference TS 2309 & WSL-INV47) , SAMC-A096895 (cross-reference TS 2317 & WSL-INV46(2)): 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-A096916 (cross-reference TS 2441 & WSL-INV74(7)): Walters Shoal Seamount, Grid WSL024 , Station ALG10956 , coll. RV Algoa , (33°08.8’ S; 43°49.1’ E) - (33°09.0’ S; 43°50.5’ E), 103–348 m depth, 29 May 2014 GoogleMaps . Additional material. TS 2443 ( WSL-INV74 (9)), TS 2452 ( WSL-INV74 (18)), TS 2455 ( WSL-INV74 (21)), TS 2456 ( WSL-INV74 (22)), TS 2549 ( WSL-INV74 (31)): Walters Shoal Seamount, Grid WSL024, Station ALG10956, coll. RV Algoa , (33°08.8’ S; 43°49.1’ E) - (33°09.0’ S; 43°50.5’ E), 103–348 m depth, 29 May 2014.

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

Description ( Fig. 6A View FIGURE 6 ). Repent-ramose form, which binds together with biogenic debris, creating a conglomerate (not shown). Length 6.5 cm, diameter 1.3 cm and thickness 0.7 cm. Surface rough and fuzzy, with small, randomly scattered oscules, ranging from <1 mm – 1 mm in diameter. Consistency and texture is soft and spongy, compressible and not easily torn. Colour in life brownish orange, pale orange in preservative.

Skeleton ( Fig. 6B, C, D View FIGURE 6 ). Choanosomal skeleton consists of a uniform network of spongin fibres, 30–60 μm in diameter, echinated by verticillate acanthostyles, with blunt (head) ends embedded in the fibre. There are no clear distinction between primary and secondary fibres. These fibres are also rarely cored with verticillate acanthostyles (embedded lengthwise in fibre). Ascending fibres usually echinated while transverse fibres are not, but this is not always the case. Interconnecting transverse fibres are often uncored, and form irregular meshes of 30–100 µm in diameter. Spongin is sparsely scattered through the mesohyl. No ectosomal specialisation.

Spiculation ( Table 4 View TABLE 4 ). Megascleres. Verticillate acanthostyles in two size classes: I) 191 (152–245) × 8 (6– 11) µm, n = 20, with 15–22 whorls of spines ( Fig. 6E View FIGURE 6 ); II) 119 (90–148) × 5 (3–6) µm, n = 20, with 12–17 whorls of spines ( Fig. 6F View FIGURE 6 ). Microscleres. Absent.

Substratum, depth range and ecology. Nine specimens found in two sleds, one which was dominated by hard live rock with many bivalves and sponges, the other host to predominantly dead shells and hydrozoans. Depth range: 72– 348 m.

Etymology. The name ‘kellyae’ was given in honour of Dr Michelle Kelly, a marine biologist and sponge taxonomist at NIWA, New Zealand for her invaluable contributions to the taxonomy, ecology and diversity of sponges from not only New Zealand and the Indo-Pacific, but also to South Africa and the WIO.

Remarks. To date, six Agelas species are described from the Western Indian Ocean. These are A. bispiculata Vacelet, Vasseur & Lévi, 1976 , A. ceylonica Dendy, 1905 , A. marmarica Levi, 1958 , A. mauritiana ( Carter, 1883) , A. oxeata Samaai, Pillay & Janson, 2019 and A. sansibarica Perino & Pronzato, 2016 ( de Voogd et al. 2024).

Agelas sansibarica contains three types of megasclere spicules:acanthostyles,acanthoxeas,and acanthostrongyles ( Manconi et al. 2016). Agelas oxeata contains two types of megasclere spicules: acanthostyles and acanthoxeas ( Lévi 1961, Samaai et al. 2019). Agelas ceylonica , which was described by Dendy (1905) from the Gulf of Mannar consist of ‘a few slender, anastomosing, sub-cylindrical branches, arising from an irregular, proliferous basal crust attached to a calcareous nodule’. Dendy (1905) describes this species as having verticillate spined styles of approximately 240 × 20 µm, while Lévi (1961) describes specimens from the Seychelles as having two classes of ‘acanthostyles’ (I) 80–275 × 5–15 µm, with 16–21 whorls; II) 100–300 × 6–15 µm, with 13–23 whorls) (see Table 4 View TABLE 4 ).

Thomas (1981) analysed specimens he identified as Agelas ceylonica from Mahe Island, Seychelles, and found smooth styles, a spicule type not mentioned in Dendy’s original 1905 description ( Dendy 1905).

Pereira and Raghunathan (2020) also observed smooth styles with plain whorls in a specimen assigned to Agelas ceylonica sensu Thomas, 1981 collected from Andaman and Nicobar Islands, India. The external morphology and presence of smooth styles indicate that the specimens studied by Thomas (1981) and Pereira & Raghunathan (2020) are distinct from Agelas ceylonica . Further research based on both morphology and molecular data is needed to clarify this species complex.

The descriptions of the other species in this region: Agelas bispiculata Vacelet, Vasseur & Lévi,1976 (verticillate acanthostyles: I) 320–400 × 14–17 µm, with 20 whorls; II) 55–120 × 6–10 µm, with 11–15 whorls), Agelas marmarica Lévi, 1958 (verticillate acanthostyles: 230 × 10 µm, with 19–21 whorls) and Agelas mauritiana ( Carter, 1883) (verticillate acanthostyles according to Lévi (1961): 150–160 × 8–12 µm, with 16–20 whorls; Manconi et al. (2016): 132 µm, with 15–18 whorls) also seem to be quite similar, especially with regards to morphology ( Table 4 View TABLE 4 ).

However, Agelas kellyae Payne, Samaai & Gibbons sp. nov. differs from the above due to the presence of very distinct, elongated spines on the smaller verticillate acanthostyles of this species, which also cover the head of the spicule, presence of smaller categories of acanthostyles and absence of smooth styles as found in A. ceylonica sensu Thomas, 1981 (ZSI/ANRC–20437) or acanthoxeas as in Agelas oxeata . The presence of smooth styles with plain whorls was not mentioned in the original description A. ceylonica by Dendy (1905) but found by Thomas (1981) when analysing additional specimens collected from Mahe Island. As we did not find styles with plain whorls or acanthoxeas, the specimen reported here from Walters Shoal constitutes a new species, Agelas kellyae Payne, Samaai & Gibbons sp. nov.