Mycale (Paresperella) policuspidifera sp. nov.

Material examined

Holotype. UFPEPOR 2869, Ilha de Bom Jesus dos Passos Píer (12°45’42.3”S – 38°38’09.1”W, Todos-os-Santos Bay, Bahia State, Brazil), col. Labimar, 23.XI.2021, 1 m depth.

Paratypes. UFPEPOR 2870 Ilha de Bom Jesus dos Passos Píer (12°45’42.3”S – 38°38’09.1”W, Todos-os-Santos Bay, Bahia State, Brazil), col. Labimar, 23.XI.2021, 1 m depth ; UFPEPOR 2874, UFPEPOR 2875 Barra do Paraguaçu (12°50’24.8”S 38°47’40.7”W, Todos-os-Santos Bay, Bahia State, Brazil), col. Labimar, 23.XI.2021, 1 m depth .

Diagnosis. This is the only Mycale (P.) with subtylostyles ranging between 165–266 µm, with spined projections bearing tridentate or polydentate pointed ends; small serrated sigmas (34–51 µm); and anisochelae in two categories.

External morphology. Thinly encrusting sponge, smooth surface. Reticulated appearance surface. The colour is yellow in situ (Fig. 8A) becoming beige in alcohol (Fig. 8B, C).

Skeleton. Ectosome with megascleres in tracts perpendicular to the surface and piercing it. Mycalostyles united by sigmas. Choanosome skeleton has thin tracts of megascleres (21–39.6–65 μm), with sigmas, anisochelae I in rosettes, among surface tracts (Fig. 8D). Moreover, mycalostyles, sigmas and anisochelae II were dispersed in the choanosome without any apparent organization (Fig. 8E, F).

Spicules (dimensions of UFPEPOR 2869). Megascleres. Mycalostyles (Fig. 9A, B) in one category only, straight or slightly curved, with rounded base (Fig. 9C, D) and pointed, tridentate or polydentate ends (Fig. 9E, F), with spined projections (165–235.8–262/3.2–3.9–4.8 µm).

Microscleres. Palmate anisochelae I (Fig. 9I) (20.6–25–28.9; alae: 9.5–13.5–16.6 µm). Palmate anisochelae II (Fig. 9J), short, well-developed, with the head accounting for approximately 50% of the total length (8.2–9.9–11.3; alae: 4.6–5.3–5.8 µm). Sigmas (Fig. 9G), C-shaped, with convex edge serrated on one or both ends, varying in approximately 3 to 10 spines (Fig. 9H) (35–39.7–43 µm).

Ecology. The holotype (UFPEPOR 2869) was found to be overgrowing an alga and the octocoral Carijoa sp., and the paratype (UFPEPOR 2875) associated with Tubastraea spp., which was overgrown around polyps.

Type locality. Northeast Brazil, Bahia State, Todos-os-Santos Bay - Bom Jesus dos Passos Island (12°45’42.3”S – 38°38’09.1”W) .

Etymology. The term “ policuspidifera ” refers to the cusp found at the pointy end (apex) of the subtylostyles due to its characteristic tridentate or polydentate nature.

Remarks. The Mycale (P.) subgenus has 18 valid species worldwide, with three species formerly registered in the Atlantic Ocean: Mycale (P.) spinosigma (Boury-Esnault, 1973), Mycale (P.) vitellina Van Soest, 2009 and Mycale (P.) atlantica Stephens, 1917 (De Voogd et al., 2024). This subgenus is characterized by the presence of serrated sigmas (Van Soest & Hajdu, 2002).

Mycale (P.) policuspidifera sp. nov. is similar to Mycale (P.) vitellina (Curaçao) in its thinly encrusting form, yellow colour in situ and possession of the same spicule categories, but the new species presents smaller subtylostyles with tridentate or polydentate apices (165–266 µm), while in the Caribbean species megascleres are styles (276– 348 µm) without any notable details as “teeth” on their apices. In addition, microscleres sigmas (34–51 µm) and anisochelae I (20–31 µm) are smaller in the Brazilian species when compared to M. (P.) vitellina which has much larger sigmas (78–93 µm) and anisochelae I (65–70 µm) (Table 3).

The new species differs from M. (P.) atlantica due to the latter species possession of toxas, absent in the new species, and lack of ornamentation on its subtylostyles. Moreover, its subtylostyles and sigmas are larger than those observed in the new species.

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Hajdu & Rützler (1998) had the opportunity to examine a fragment from the holotype of M. (P.) spinosigma (MNHN D NBE 968) and were unable to find any anisochelae. Furthermore, the characteristic sigmas were very rare, which led these authors to suspect they might actually be contaminants. We consider thus that M. (P.) spinosigma is best treated as a species inquirenda and refrain from any comparison with our newly proposed species.

Mycale (P.) policuspidifera sp. nov. shares the presence of megascleres with bidentate, tridentate or polydentate apices with Mycale (P.) curvisigma (Lévi, 1969), M. (P.) serratohamata (Carter, 1880), M. (P.) moluccensis (Thiele, 1903) and M. (P.) sceptroides Van Soest, Aryasari & De Voogd, 2021 . However, all species mentioned present megascleres that are substantially larger than those of Mycale (P.) policuspidifera sp. nov. (Table 3), which is considered a well distinguished new species.