Placospongia melobesioides Gray 1867

Description: Thinly encrusting sponge, 5-10 cm wide, 5 mm thick. Surface composed of rough armoured polygonal plates with raised edges (surface contracts when touched and gaps between plates close). Sandpapery feel; dark blackish-brown, maroonish-black interior. Habitat: eulittoral rocky flats, between and on coral rubble, in crevices. Distribution: Indo-Pacific (Richmond, 1997).

Holotype BMNH 52.4.1.14 dry, chalky white angular branches, hard. Other examined material encrusting to branching, hard, thicker specimens slightly compressible. External morphology follows the description of the genus. Size ranging between 5-50 cm, though encrusting specimens may be larger growing within crevices. Ectosome color in life ranging from purple, dark black brown, chocolate brown, orange brown to light beige (Fig. 1, 2). Choanosome pale beige. After preservation color of ectosome is similar to live color. Spicules. Holotype BMNH 52.4.1.14 (Fig. 6): Megascleres large straight tylostyles with blunt ends 670-880-1010 × 10-13-18 × 10-16-20 μm, small concave to straight tylostyles with sharp ends 205-293-420 × 5-10-13 × 5-10-13 μm. Microscleres selenasters 58-63-68 × 45-52-68 μm, spherasters 15-17-18 μm (five measurements, not abundant), spherules 1-2-3 μ m. The range within the examined material (Table 1): large tylostyles 460-1040 × 5-16 × 8-18 μ m, small tylostyles 190-470 × 3-13 × 3-15 μ m, selenasters 45-83 × 30-65 μ m, spherules 1-3 μ m, spherasters only found in singles in some individuals 15-20 μ m. Streptasters and microrhabds absent. Skeleton. As description of genus with addition of sporadic spherasters lodged amidst selenasters in cortex and high abundance of spherules in choanosome and cortex.

Type locality: Borneo. Distribution from Seychelles to Micronesia (Fig. 9, Table 3). Possibly further east to Central Pacific.