Ancorina corticata Lévi, 1964

Ancorina corticata Lévi, 1964 View in CoL

Figure 2A–L View FIGURE 2 , Table 1 View TABLE 1

Material examined. SAMC-A096923 (cross-reference TS 2475 & WSL-INV84(4)) , SAMC-A096924 (cross-reference TS 2476 & WSL-INV84(5)): 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 .

Description ( Fig. 2A View FIGURE 2 ). Massive, amorphous form. Length 9.4 cm, width 5.6 cm and thickness 3.4 cm. Surface microhispid, prickly to the touch. A few oscules evident on the ridge (0.5–1 mm) and several (1–2 mm) on the underside of specimen SAMC-A096924. Texture firm, dense and slightly rubbery. Barely compressible, not easily torn. Ectosome (~ 2 mm) present, not separable from the choanosome and yellow in life, white in preservative. Colour in life dark brown with yellowish tinge and darker brown, almost black ridges externally and paler brown internally. In preservative, dark brown externally and paler brown internally. Water retentive, leaving a brown exudate on tissue paper.

Skeleton ( Fig. 2B View FIGURE 2 ). Choanosomal skeleton consists of radiating tracts of plagiotriaenes and oxeas. Tracts of large oxeas occur between the plagiotriaenes in mid- and deep choanosomal layers of the sponge. Oxyasters abundant and scattered throughout. Towards the surface, the tracts become denser and are entirely composed of plagiotriaenes with overlapping cladi. Ectosomal skeleton comprises a thick discernible layer with radiating plagiotriaene tracts that pierce the surface, through a dense (up to ~100 µm thick) layer of sanidasters.

Spiculation ( Table 1 View TABLE 1 ). Megascleres. Oxeas, smooth, straight to slightly bent, with no easily discernible size classes (continuous) and large size range: 1362 (728–2018) × 20 (6–37) µm, n = 20 ( Fig. 2C, D View FIGURE 2 ). Plagiotriaenes with short, stout cladi, rhabdome straight to slightly bent ( Fig. 2E, H View FIGURE 2 ), with juvenile forms also present ( Fig. 2F, G, H View FIGURE 2 ): I) Adult form, rhabdome 1710 (1550–2079) × 39 (33–47) µm, cladome 153 (130–179) µm, cladi 91 (75–117) µm, n = 20; II) juvenile form, rhabdome 792 (448–1037) × 15 (6–24) µm, cladome 49 (20–84) µm, cladi 22 (8–38) µm, n = 20. Microscleres. Oxyasters with ~10 rays, smooth or with hooked spines: 11 (9–15) µm, n = 20 ( Fig. 2I View FIGURE 2 ). Acanthoxyasters with 5 rays and hooked spines; some with vestigial actines with hooked spines, variable in form and spinosity: 19 (15–24) µm, n = 20 ( Fig. 2J, K View FIGURE 2 ). Sanidasters, acanthose, irregularly spined: 6 (5–7) µm, n = 20 ( Fig. 2L View FIGURE 2 ).

Substratum, depth range and ecology. Two specimens found in one sled on rocky substrate in association with tube worms and algae. Depth range: 28– 34 m.

Distribution. Mozambique (Inhaca Island), Mbotyi (Eastern Cape), Walters Shoal Seamount

Remarks. The present material conforms to Ancorina Schmidt, 1862 as diagnosed by a distinct cortex, the presence of oxeas and triaenes as megascleres and microscleres comprising sanidasters and euasters ( Uriz 2002). Only 14 species are currently accepted within Ancorina according to the World Porifera Database ( de Voogd et al. 2024), two of which are described from the Western Indian Ocean (WIO) & South Africa: Ancorina corticata Lévi, 1964 ( Mozambique, WIO) and Ancorina nanosclera Van Soest, 2024 ( South Africa).

Ancorina nanosclera possesses anatriaenes; however, we did not find any anatriaenes in our specimens. These specimens closely resemble Ancorina corticata , as described from Mozambique, in terms of external morphology. They are dark brown to reddish in color and exhibit the following spiculation: oxeas measuring 2000–2400 × 50 µm, plagiotriaenes with a rhabdome size of 1400 × 70 µm and cladi measuring 130–150 × 50 µm, oxyasters at 15–20 µm, and sanidasters at 6 µm (see Table 1 View TABLE 1 ). This species has also been recorded from South Africa (Mbotyi, Eastern Cape) by Lévi (1967), with the following spicule measurements: oxeas measuring 1500–2400 × 50– 65 µm, plagiotriaenes with a rhabdome size of 1000–1500 × 25–65 µm and cladi measuring 55–175 µm, oxyasters at 15–25 µm, and sanidasters at 7 µm (see Table 1 View TABLE 1 ). Ancorina corticata was also described by Samaai & Gibbons (2005) from the southwest coast of South Africa. The specimens from the west coast have much larger spicules, and the sanidasters appear significantly different from those found in our samples.

The species discussed here is tentatively assigned to Ancorina corticata , based on the similarities outlined above. We have not examined or revised the type material although we observe some differences in spicule measurements: it is challenging to argue that this size variation is significant enough to warrant the description of a new species, especially since our knowledge of spicule size variation in A. corticata is limited. Table 1 View TABLE 1 presents spicule measurements from Lévi (1964, 1967) alongside those from our specimens, providing some context for the observed variation. We have not performed any SEM analysis on the type of A. corticata but Lévi's drawings (1964, 1967) suggest that the oxyasters likely have smaller spines like those found in our specimens.