Spongionella pulchella (Sowerby, 1804) Fig. 7

Spongia pulchella Sowerby, 1806: 87.

Description.

Growth form of Mediterranean specimens cushion-like, small (2 cm in diameter, 5-10 mm in thickness). Colour grey-greenish-brown. Consistency soft and elastic . Surface finely conulose with conules supported by tips of ascending fibres. Inhalant apertures not visible, oscules small (0.5-1 mm) and rare. Flagellate chambers large (70-80 µm) with small choanocytes. Skeleton network typical of the genus, ex tremely regular and practically indistinguishable from that of Spongionella gracilis . Fibres laminate, light and transparent, with axial pith lacking of inclusions that, when evident, shows a typical aplysillid structure. After Topsent (1929): primary fibres of a single dimensional class (25-35 µm); rare and irregular secondary connecting tracts (7-25 µm); meshes generally quadrangular 120-300 µm in diameter.

Habitat.

Cave, coralligenous community, Posidonia oceanica meadow, artificial reef, detritic bottom. Bathymetric range 4-380 m.

Mediterranean Caves.

Meda Petita, Petita de la Vaca caves (Balearic Sea); Endoume, Figuier, Trèmies caves (Gulf of Lions); Farà Cave (Aegean Sea) (Pouliquen 1972; Bibiloni et al. 1984a; Pronzato and Manconi 2011; Gerovasileiou and Voultsiadou 2012).

Remarks.

The Mediterranean specimens ascribed to this species, are very different from the Atlantic ones.