Eurypon potiguaris sp. nov. (Figures 1, 4–5, Table 1)

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

Type specimens: Holotype. UFPEPOR 1949, Bacia Potiguar (04° 36.7198' S – 036° 46.7554' W), Rio Grande do Norte State, Brazil, depth 157 m, trawl, col. Petrobras, (22/V/2011).

Diagnosis. Thinly encrusting sponge with a spicule complement composed by large tylostyles (1000–2315 / 6– 10 µm), acanthostyles I (119–300 / 6–12 µm), acanthostyles II (62–98 / 2–8 µm) and oxeas (207–550 / 2–5 µm).

External morphology (Fig. 4A–B). Thinly encrusting sponge, approximately 0.5 mm thick. Hispid surface, consistency fragile and oscula absent. Colour in life is unknown and brown when preserved (80% ethanol).

Skeleton (Fig. 4B). No special ectosomal skeleton. Choanosomal skeleton composed of typical microcionid structure. Tylostyles, acanthostyles and oxeas protruded through surface forming projections of single spicules over the sponge.

Spicules (Fig. 5A–H). Choanosomal tylostyles, eventually subtylostyles (1000– 1418.5 –2315 / 6– 8.1 –10 µm): elongated, smooth, curved, and with blunt tips and rounded tyla (Fig. 5A–B); Acanthostyles I (119– 205.5 –300 / 6– 9.0 –12 µm): long, robust, erect to slightly curved, with few little spines over the shaft, more abundant at the sponge basement (Fig. 5E–F); Acanthostyles II (62– 74.3 –98 / 2– 4.1 –8 µm): smaller than acanthostyles I, thin, straight, with big curved spines (hook-shaped) directed to the base projected all over the shaft (Fig. 5G–H); Thin oxeas (207– 443.7 –550 / 2– 2.7 –5.5 µm): long, slightly curved, and with blunt tips (Fig. 5C–D).

Distribution and ecology (Fig. 1). Known from the type locality Potiguar Basin (Rio Grande do Norte State, Northeastern Region, Brazil), at 157 m. Eurypon potiguaris sp. nov. was found over a sand aggregate on the bryozoan Cupuladria sp.

Etymology. The species name refers to the type locality Potiguar Basin, Brazil.

Remarks. Eurypon potiguaris sp. nov. differ from other Atlantic species of the genus, in spicules complement composed by large tylostyles, two categories of acanthostyles and oxeas, and dimensions (Tab. 1). The most similar species are E. mucronale and E. urizae, which have (sub)tylostyles, two size categories of acanthostyles and oxeas. However, the new species has much smaller tylostyles and oxeas are greater than those exhibited by E. urizae and E. mucronale (Tab. 1). Eurypon fulvum and E. major share with E. potiguaris sp. nov. the presence of choanosomal tylostyles, acanthostyles and oxeas. Nevertheless, they present only one category of acanthostyles and differ regarding the spicules dimensions (Tab. 1). Eurypon potiguaris sp. nov. differs from E. clavilectuarium, E.

miniaceum and E. suassunai by the presence of choanosomal subtylostyles and styles. The new species differ from E. hispidulum, E. incipiens, E. scabiosum and E. simplex for presenting oxeas. Acanthostyles are absent in E. lictor and E. topsenti . Eurypon clavatella, E. clavatum, E. cinctum, E. coronula, E. distyli, E. longispiculum, E. pulitzeri nom. nov., E. radiatum, E. toureti and E. viride present only one category of acanthostyles, while the new species has two acanthostyle categories. Eurypon potiguaris sp. nov. differs from E. oxychaetum sp. nov. in spicules complement.