Petrosaspongia nigra Bergquist, 1995

pictures.

Description

External features

Massive–lobulose with an unarmoured microconulose surface. Each conule ends in a thin projecting fibre (Fig. 1 A). Consistency stony, incompressible. Oscules spread on the surface, 1–2.8 mm in diameter. Colour blackish outside, beige inside, in alcohol.

Skeleton

Reticulate with a dense network of secondary fibres forming meshes 80–225 m in diameter. They form fenestrate plates when they join the primary fibres.

Primary fibres: 355–790 m in thickness, strongly cored by foreign debris (Fig. 1 B)

Secondary fibres: 20–80 m (Fig. 3 A), laminated and completely free of foreign debris. (Fig. 1 B–C & Fig. 3 C). Through SEM, the surface of the secondary fibres appears rippled in a longitudinal direction (Fig. 1 C).

Tertiary fibres: Very thin, rare.

Choanosome containing abundant sand and other foreign materials (Fig. 1 D).

Distribution: Southwest Pacific region, New Caledonia islands, from 10 to 38 m depth.

Note. The re–examination of the holotype allowed us to measure the skeletal elements, and our results provide larger fibre diameters (particularly for the primary fibres) from those given by Bergquist (1995).