Family Placospongiidae Gray, 1867

Abstract

Placospongiidae Gray (Demospongiae, Hadromerida) has the typical radial skeleton structure of Hadromerida and Spirastrella -like tylostyle-spiraster spicule complement but stands out by the possession of a rigidly cemented cortex of large microscleres. The cortical spicules are ovoid or bean-shaped (selenasters) or dumbbell-like (amphinolasters). The cortex is broken up into distinctive plates that are separated by contractible grooves containing oscula and ostia. Species are encrusting or branching massive and most occur in shallow tropical and subtropical waters, from the intertidal to almost 200 m. The family, until recently considered monotypic, includes two genera, Placospongia (including Physcaphora) and Onotoa (including Amphinolana).