Familia Thorectidae

Bergquist, 1980

Definition: Order Dictyoceratida. Encrusting, massive, tubular and stalked growth forms. Surface may be conulose and armoured with sand or detritus and thrown into ridges, or conulose and unarmoured resembling the Spongiidae. Choanosomal skeleton consists of regularly or irregularly reticulate spongin fibres, often with almost perfectly regular meshes (Cacospongia scalaris fibres). Fibres are laminated in cross-section, with clear zones of disjunction between sucessive layers, and with diffuse central pith in primary fibres at least, although features of both classes of fibres may be obscured by incorporated foreign debris. Pith is not sharply disjunct from the investing more dense layer, as in the pith in the Verongida, but rather merges into the outer layer of fibres. The mesohyl of Thorectidae is usually more collagenous than in the Spongiidae, and macroscopically appears slightly fleshly. Choanocyte chambers are spherical and diplodal.

Remarks: 32 nominal genera of which 11 valid genera are included. Originally, also the three genera with spongin filaments were included in this family, but these are now separated in a family Irciniidae. Review: Bergquist (1980).

Source: Hooper's Internet Sponge Guide.

Genera represented in the area:
Cacospongia Schmidt, 1862 (type species C . mollior Schmidt, 1862): surface finely and evenly conulose superficially resembling Spongia; surface never armoured; texture compressible and easily torn; fibres stratified, harsh, brittle; primary fibres are simple and cored with detritus, to some extent masking the granular pith; secondary fibres clear, regularly spaced, forming an almost rectangular reticulation, with or without pith (Bergquist, 1980).

Hyrtios Duchassaing and Michelotti, 1864 (type species H . proteus Duchassaing and Michelotti, 1864) (syn. Collospongelia Ferrer-Hernandez, 1922; Duriella Row, 1911; Dysideopsis Lendenfeld, 1888; Heteronema in part, Keller, 1889; Oligoceras Schulze, 1879; Thorectopsamma Burton, 1934): texture ranges from compressible to quite firm or even brittle, reflecting the degree of development of the skeleton and debris in the skeleton; surface distinctly conulose, with primary fibres terminating in the conules and sandy inclusions within fibres appearing whitish against the dark sponge surface; collagenous mesohyl containing extraneous detritus; both primary and secondary fibres fully charged with detritus to some extent obscuring stratified nature of spongin fibres; primary skeleton shows some fasciculation near the surface (Bergquist, 1980).

Species included:
Cacospongia scalaris
Hyrtios collectrix
Hyrtios dendyi

Species not treated here:
Cacospongia mollior Schmidt (1862), S. Portugal

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