Sphaerotylus bouryesnaultae Van, 2017, sp. nov.

Sphaerotylus bouryesnaultae sp. nov.

Figures 77 a–e

Material examined. Holotype RMNH Por. 6303, Suriname, ‘ Luymes O.C.P.S. ’ Guyana Shelf Expedition, station K101B, 7.3783°N 54.3583°W, depth 93 m, rectangular dredge, 17 April 1969.

Description. (Fig. 77 a) Globular individual of approximally 1.2 cm in diameter, provided with a single conical papilla 6 mm high 5 mm in diameter. Color beige in alcohol. Upper surface surrounding the papilla has a ‘forest’ of individual long spicules (exotyles) protruding 2–3 mm above the ectosome. Consistency firm.

Skeleton. Similar to Polymastia, consisting of long subtylostyles radiating from the inner core to the surface, a subectosomal layer of intermediate-sized tylostyles arranged at right angles to the radiating subtylostyles, and a surface palisade of small tylostyles. Exotyles pass individually through the outer layers and protrude far beyond the surface.

Spicules. (Figs 77 b–e) Exotyles, subtylostyles, intermediate tylostyles, small tylostyles.

Exotyles (Figs 77 b) provided with a tylote part with faint tyle (Fig. 77 b1) at the inner end and a rugose elongate swelling at the outer end (Fig. 77 b2), usually rather strongly curved; few of these exotyles could be retrieved undamaged, three measured 4–4.5 mm x 8–12 µm, swollen rugose ends up to 45 x 10 µm.

Subtylostyles (Figs 77 c,c1,c2), heads elongate with subterminal restricted part, fusiform, distinctly polytylote at the bluntly rounded end (Fig. 77 c2), dominating the skeleton, 840– 1165 – 1458 x 13 – 17.8 –24 µm.

Intermediate tylostyles, distinct tyles, straight, ending thinly, 528– 718 – 1132 x 9 – 12.1 –16 µm.

Small tylostyles, globular tyle, usually curved, 105– 119 –147 x 3 – 3.9 –5 µm.

Distribution and ecology. Guyana Shelf, sandy bottom, at 93 m depth.

Etymology. Named after Dr. Nicole Boury-Esnault (Station Marine d’Endoume, Marseille) in acknowledgment of her important polymastiid studies and of her efforts to promote molecular approaches for the phylogeny of sponges.

Remarks. This specimen represents the first record of the genus Sphaerotylus from the Central West Atlantic. The exotyle spicules of the new species with their curved shaft and elongate exotyles appear distinct among all the known species. The genus was recently reviewed by Plotkin et al. (2016a) including the descriptions of three new species, but none of these were from the Central West Atlantic region. Perhaps the closest species is South African Sphaerotylus strobilis Plotkin, Morrow, Gerasimova & Rapp, 2016 as it has the exotyle swellings also elongately irregular like in the present new species, but these exotyles are only up to 632 µm long in P. strobilis (against 4.5 mm in the present species). Also the other spicules are distinctly different in size, whereas the shape differs with several papillae curved and ridged in S. strobilis. Elsewhere the genus is common in boreo-arctic waters (both in the North Atlantic and the North Pacific), and in Antarctic waters. Only a single record was so far known from the tropical zone, S. exospinosus Lévi, 1993 from New Caledonia, at 570–610 m depth.