Oceanapia magna Neto & Nascimento & Cavalcanti & Pinheiro 2018, sp. nov.

Oceanapia magna sp. nov.

Figures 5–6, Tables 1–2

Type locality: Brazil: Rio Grande do Norte State: Potiguar Basin.

Type specimens: Holotype. UFPEPOR 1998 (04°44'53.7’’S 36°25’27.4’’W), Potiguar Basin, Rio Grande do

Norte State, Brazil, depth 108 m, trawl, coll. Petrobrás (23/V/2011). Paratypes. UFPEPOR 2266 and UFPEPOR 2285, collected at the type locality.

Diagnosis. Semispherical sponge with large fistulae, large oxeas (125–408 / 2–14 µm) and sigmas (10–45 µm).

External morphology (Fig. 5A–B). The holotype consists of a semispherical body of 30 cm (diameter). Despite its large size, part of the specimen remained in situ at the time of collection, and it can be deduced that the size of the sponge was larger. On the upper side, there are numerous digitated fistulae of irregular shape, fragile and easily broken. Simple fistulae (0.7–6.5 x 0.5–1.8 cm, length x width) and fused fistulae (3.5–8.5 x 1.5–4 cm, length x width). Hispid and irregular surface covered by other sponges. Surface hard and firm, forming a cortex (0.5–2 cm, thickness). Colour brown when preserved (ethanol 80%), unknown in life.

Skeleton (Fig. 5C–D). Ectosome organic, formed by a tangencial skeleton of single oxeas and debris, supported by a subdermal reticulation of criss-crossing spicule tracts (50– 94.6 –133 µm, diameter, meshes 100– 372.2 –633 µm, diameter). The choanosomal skeleton is an irregular network of multispicular tracts (83– 174.2 –333 µm) forming irregular meshes (100– 410.1 –1165 µm) and some ascending multispicular tracts. The fistulae have an ectosomal skeleton quite differentiated, formed by multispicular tracts and irregular meshes interconnected by single spicules.

Spicules (Fig. 6). Oxeas (125– 218.3 –408 / 2– 8.8 –14 µm): smooth, straight and slightly curved, with variably shaped points (acerate, hastate and blunt) (Fig. 6A – B). Sigmas (10– 18.2 –45 µm): smooth, thin and rare, found in the sponge body, absent in the fistulae (Fig. 6C).

Distribution and ecology. Known only from Potiguar Basin, Rio Grande do Norte State, Brazil, from a slope at 108 m deep (Fig. 1).

Etymology. Adjective derived from Latin magna and refers to the large size of the specimens.

Remarks. The most similar species are O. atlantica, O. carotta and O. oleracea. Oceanapia atlantica is amorphous, and its oxeas and sigmas are larger than the new species. Oceanapia carotta has a spherical shape and its fistulae are not digitiform, and oxeas are smaller than found in O. magna sp. nov. (Tables 1–2). Oceanapia oleracea has a spherical shape with fistulae on the top, and its oxeas are smaller in length and width than the new species (see Tab 1). Compared to other species of Oceanapia in the Atlantic Ocean, Oceanapia magna sp. nov. is distinguished from O. bartschi, O. hondurasensis and O. niduliformis by the presence of strongyles. Oceanapia magna sp. nov. differs from O. cordia sp. nov., O. topsenti nom. nov., O. aerea, O. ascidia, O. coriacea, O. elongata, O. fibulata, O. isodictyiformis, O. nodosa, O. nodulosa, O. peltata, O. penicilliformis, O. reticulata and O. robusta by their absence of microscleres. Oceanapia magna sp. nov. differs from O. cancap and O. stalagmitica because they have toxas which are not found in the new species. Oceanapia hetcheli nom. nov. has as spicule complement oxeas and raphidiform oxeas, while Oceanapia magna sp. nov. has oxeas and sigmas.