Family Dysideidae Gray, 1867

Abstract

Dysideidae Gray (Demospongiae, Dictyoceratida), including Spongelidae, consists of five valid genera, with approximately 43 species described worldwide. In Dysideidae spongin fibres making up the anastomosing skeleton are always concentrically stratified but to varying degrees. As in some members of the Thorectidae, this character is affected in development by the extent to which the sponge incorporates foreign debris into the fibres. Pith components, as optically distinct central regions of the fibres, are evident, except where fibres are packed with detritus. The choanocyte chambers are eurypylous, and the matrix contains only light collagen reinforcing. The sponges are histologically simple, with few secretory cell types present. The sponge texture is soft and compressible unless rendered brittle by inter- stitial detritus. Incorporation of debris into both fibres and matrix is frequent. The sponge surface is always conulose, but the size, shape and arrangement of conules ranges from very small, fine and even, to large and irregular, or tuberculate. Dysideid genera are distinguished by their general form, skeletal morphology and the presence of an intrafibre core of foreign debris.