Gray, 1867
Definition: Dendroceratida with encrusting, massive or branching growth forms, typically with conulose surface, although this is developed to various degrees, and often has characteristic sculpturing produced by tangential spongin fibres cored by sand, giving it a delicate lace-like appearance. Texture is usually soft and compressible, sometimes brittle due to interstitial detritus. Choanosome consists of a wide reticulation of spongin fibres, concentrically stratified although to varying degrees. There are laminated fibres and they are cored by a central pith, but this may be obscured by abundant detritus which is frequently incorporated into the spongin fibres. Mesohyl contains only light collagen reinforcing. Large and eurypylous choanocyte chambers, measuring 60 to 120 µm long and 40 to 65 µm broad (Dysidea fragilis skel).
Remarks: 14 nominal genera are presently included in this family, of which only 3 are valid. Review: Bergquist (1980).
Genera represented in the area:
Dysidea Johnston, 1842 (type species Spongia fragilis Montagu, 1818) (syn. Aulena Lendenfeld, 1885; Duseideia Johnston, 1842; Duseidea Delage,1899; Dysidia Agassiz, 1846; Dyseideia Lieberkühn, 1855; Haastia Lendenfeld, 1888; Halmopsis Lendenfeld, 1885; Sarcocornea Carter, 1859; Spongelia Schmidt, 1862): surface always conulose, with distinct sand-tracery (cobweb-like) on the surface interconnecting adjacent conules; all fibres are concentrically stratified, filled with pith, and filled with detritus, but collagen is only light in mesohyl (Bergquist, 1980).
Spongionella Bowerbank, 1862 (type species Spongia pulchella Sowerby, 1806) (syn. Megalopastas (in part) Dendy, 1905; Velinea Vosmaer, 1883): skeleton is a compact reticulation of uncored primary and secondary fibres in which concentric laminations and a pith component are always apparent although variable in extent; skeletal arrangement is regular, almost perfectly rectangular in the type species; primary fibres are extended into fine tapered projections and surface is finely conulose (Bergquist, 1980).
Species included:
Dysidea avara
Dysidea fragilis
Spongionella pulchella
Species not included:
Dysidea pallescens (Schmidt, 1862), cf. Ackers et al., 1992, Lough Hyne, SW Ireland (needs to be verified)