Neophrissospongia nana Manconi & Serusi 2008

Known from a single specimen. Growth form as a large thick encrusting plate (10-12 x 5-7 cm) with a wide base adhering to the substrate and rounded margins. The sampled portion (holotype, 5 x 3.5 cm in width, ca. 1.2 cm in thickness) is one third of the entire living specimen. Colour white ice both in vivo and in spirit, except for a brown degenerated portion at the margin. Consistency stony, harder toward the basal portion. Surface even without asperities, aconulose. Ectosome with irregular sub-dermal canals. Inhalant apertures (0.2-1.2 mm in diameter) grouped in slight concavities along the sponge margins. Exhalant areas scattered on the top surface with grouped oscules (0.5-1 mm in diameter) each with a well-developed vertical atrial canal. Ectosomal skeleton armed by a layer of radially arranged dichotriaenes megascleres of two types. Dichotriaenes with cladomes (145-270 μm in diameter) bearing few tubercles (10-20 μm in height) rarely subdivided at the upper surface of protoclades (20-50 x 10-20 μm, usually 20-30 μm in length) and deuteroclades (50-100 x 10-20 μm, usually 50-70 μm in length). Deuteroclades sometime with branched tips. Rare dichotriaenes with entirely smooth cladomes (93-172 μm in diameter) and scarcely developed clades also present with no differential localization. Rhabdomes with blunt to acute tips (290-540 μm in length) usually smooth, sometimes bearing a few large acute spines or tubercles (up to 30 μm in length) along the axis. Extremely rare triaenes with a few tubercles on the clades also present. Other ectosomal spicules of two types, namely asterose and monaxial. Microscleres as streptaster/amphiaster with short spiny rays (5-15 μm in length) in a variable number (3-7) with blunt tips. Notably thin styles/sub-tylostyles (59-86 μm, < 3 μm in thickness) scattered and tangentially embedded in subectosomal membranes in both the inhalant and exhalant areas.
Architecture of the choanosomal skeleton as a loose network of slender dicranoclone desmas, strongly articulated along the canals of the aquiferous system. Desmas (280-360 μm) with rounded tubercles (5-35 μm in height, usually 10-15 μm) bearing smooth heads. Slender small young desmas with a smooth surface also present.

Type locality: Grotta delle Terrazze n. 2740 Catasto Speleologico Regionale (40°34’16”N 08°13’43”E), Punta Giglio Promontory, Alghero, NW Sardinia, 10.iv.2004, R. Barbieri coll. by SCUBA diving.
Material studied: Corallistes nolitangere Schmidt, 1870, p. 23, MNHN DT 781, Fayal, Campagne Prince Albert de Monaco Azores I, leg. E. Topsent, 1 slide; MOM 2144-0-04-0191, large specimen, collection E. Topsent, presumably Azores; AZR 71, collection G. Pulitzer-Finali, 4 slides, unknown locality of Azores.