Cyamon arguinense van Soest, Carballo & Hooper 2012

Thin crust, (Fig. 6A) hispid surface. Color red (alive), dirty white (alcohol). Consistency soft, easily damaged, size 2.5 × 1.5 cm × 2–3 mm. Skeleton: columnar bundles of megascleres issuing from a basal layer of polyactines. Columns consist of a single long subtylostyle sheathed in a tight bundle of fusiform centrotylote styles; bundles separate, interconnected only near the substratum. Spicules of three types: subtylostyles (assumed to be homologues of the long thin styles), centrotylote styles (assumed homologues of the short thin styles), polyactines (short thick styles apparently lacking). Long thin (subtylo-)styles (Fig. 6B, B1) with prominent heads, and bluntly rounded pointed ends, 1229–1482.1–1668 × 12–13.9–18 µm. Short thin styles, fusiform, centrotylote (Fig. 6C, C1), tyle slightly excentric, rounded end tapering, 244–521.5–719 × 2.5–6.4–9 µm. Polyactines, (Fig. 6D) predominantly four-claded, (a few five-claded forms were observed), basal cladus with coarse recurved spines, lateral cladi entirely smooth, basal cladus 51–58.6–69 × 5–6.5–8, lateral cladi 31–55.7–78 × 4–6.1–8 µm.

(Fig. 5). So far known only from the sandstone ridges of coastal flats of the Banc d’ Arguin, Mauritania, West Africa.