Mycale (Naviculina) oxeata, Mácola & Nascimento & Pinheiro & Neves & Johnsson, 2025

Mycale (Naviculina) oxeata sp. nov.

Material examined

Holotype. UFPEPOR 2867 Marina de Itaparica Píer (12°53’20.9”S – 38°41’04.2”W, Todos-os-Santos Bay, Bahia State, Brazil), col. Labimar, 15.X.2020, 1 m depth. GoogleMaps

Paratypes. UFPEPOR 2868, UFPEPOR 2871, UFPEPOR 2872 Marina de Itaparica Píer (12°53’20.9”S – 38°41’04.2”W, Todos-os-Santos Bay, Bahia State, Brazil), col. Labimar, 15.X.2020, 1 m depth GoogleMaps ; UFPEPOR 2873 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 GoogleMaps .

Diagnosis. This is the only Mycale (N.) known with the presence of oxeas as megascleres, and two size categories of palmate anisochelae as microscleres.

External morphology. Finely encrusting sponge with transparent membrane similar to a peel. The colour is yellow in situ, turning beige when preserved in alcohol ( Fig. 6A, B View FIGURE 6 ). Oscules not observed.

Skeleton. An ectosomal skeleton with triangular reticulation of paucispicular bundles composed by megascleres ( Fig. 6C View FIGURE 6 ). Choanosome skeleton with oxeas and mycalostyles dispersed in less quantity, microscleres anisochelae I in rosettes, anisochelae II, sigmas I/II and naviculichelae dispersed in the choanosome ( Fig. 6E, F View FIGURE 6 ). Tangential section with bundles of mycalostyles visible, and microscleres dispersed with no apparent organization ( Fig. 6D View FIGURE 6 ).

Spicules. Megascleres. (dimensions of holotype UFPEPOR 2867). Mycalostyles ( Fig. 7A View FIGURE 7 ) were in one category (301–336.3–364/3.9–5.9–7.9 μm). Oxeas ( Fig. 7B View FIGURE 7 ), slightly curved, robust (76–99.3–129/4.3–5.5–7.2 μm).

Microscleres. C-shaped sigmas in two size categories ( Fig. 7C, D View FIGURE 7 ) (I: 33–41.2–50 μm) (II: 8.7–10.2–11.6 μm). Palmate anisochelae I, long and robust ( Fig. 7E View FIGURE 7 ), alae 52% of the total size of the spicule (31–37.9–41 μm; alae:15.3– 19.1–22.9 μm). Palmate anisochelae II, short, ala 56% of the total size of the spicule ( Fig. 7F View FIGURE 7 ) (8.7–10.2–11.6 μm; alae: 5.3–5.6–5.9 μm). Naviculichelae, with near fusion of both frontal alae ( Fig. 7G View FIGURE 7 ) (13–14.5–15.6 μm).

Ecology. The sponges were found on artificial substrate piers (Marina de Itaparica Island and Bom Jesus dos Passos Island) at 1 m depth. Mycale (Naviculina) oxeata sp. nov. was observed to overgrow Tubastraea spp. and the octocoral Carijoa riisei ( Duchassaing & Michelotti, 1860) .

Type Locality. Northeast Brazil, Bahia State, Todos-os-Santos Bay, Marina de Itaparica Píer (12°53’20.9”S – 38°41’04.2”W) GoogleMaps .

Etymology. The term “ oxeata ” refers to the presence of oxeas as an additional category of megascleres in the new species, which are absent in other species of the subgenus Naviculina .

Remarks. Mycale (Naviculina) has 14 species accepted worldwide, with three species recorded in Brazil: Mycale (N.) arcuiris , Mycale (N.) purpurata and Mycale (N.) diversisigmata ( Muricy et al., 2011; De Voogd et al., 2024) ( Table 2 View TABLE 2 ).

The new species differs from all species of Mycale (Naviculina) mainly by the unique presence of oxeas as megascleres, which are absent in every other species, in combination with mycalostyles, two categories of palmate anisochelae and only one of naviculichelae.