Spirastrella aff. decumbens Ridley, 1884

Fig. 5

Diagnostic features.

A thin encrusting sponge with a soft texture and a smooth surface. The living specimens exhibit a salmon-pink or orangish color. The ectosome of the sponge contains numerous microscleres (spirasters), forming the characteristic tangential crust found in this genus. In the choanosome, the megascleres are irregularly arranged tylostyles with well-formed, usually spherical heads (Calcinai et al. 2006). Our specimen shows spirasters with ornamented rays (Fig. 5 d) that are not mentioned in the Calcinai et al. (2006) report from Vietnam.

Distribution and ecology.

This species is present in the Australian region, New Caledonia, the Philippines, and Vietnam. In Indonesia is recorded from Ambon; this is a first record for the Spermonde Archipelago (Langkai Island; reef flat).