Family THORECTIDAE Bergquist, 1978

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Diagnosis

Wide range of growth forms, from encrusting pads to massive, upright, lobose, caliculate or digitate structures. The surface may be armoured, and is frequently thrown into ridges and hollows. Where unarmoured the surface is typically conulose. The skeleton comprises primary, secondary and sometimes tertiary fibres. The skeletal reticulum is usually regular, frequently with almost perfectly rectangular meshes. The spongin fibres making up the anastomosing skeleton are laminated in cross-section, with clear zones of disjunction between successive layers. The central region of each fibre is a diffuse pith that is not sharply disjunct from the denser investing layer, as is the pith in the Verongida, but merges into the outer layer. A pith is always evident in the primary fibres, though it may be obscured by an axial core of foreign material within fibres, and may extend into the secondary elements of the skeleton. Some fibres can become extremely stout, and in some genera may form light and simple, to strong, complex fascicles. Primary fibres can be greatly reduced in number, or difficult to distinguish from sub-primary fibres. Thorectids do not have the fine filaments seen in Irciniidae species. Choanocyte chambers are spherical to oval, and diplodal. The mesohyl is more collagenous than in the Spongiidae, and macroscopically can appear fleshy. Its cellular composition can be complex, and some secretory cell types, the spherulous cells, resemble those of the Verongida.

ID Keys

KEY TO SUBFAMILIES

(1)Foliose, lamellate or folio-digitate; tertiary fibres in skeleton (except in one genus) -------------- Phyllospongiinae
Variable form; tertiary fibres in only two non-folio-lamellate genera ------------------------------------------ Thorectinae

Diagnosis References

Cook, S.D.C. & Bergquist, P.R. 2002. Family Thorectidae Bergquist, 1978. pp. 1028-1050 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1. [1028]

General References

Bergquist, P.R. 1980. A revision of the supraspecific classification of the orders Dictyoceratida, Dendroceratida and Verongida (Class Demospongiae). New Zealand Journal of Zoology 7: 443-503 figs 1-25 pls

Bergquist, P.R. 1995. Dictyoceratida, Dendroceratida and Verongida from the New Caledonia Lagoon (Porifera: Demospongiae). Memoirs of the Queensland Museum 38(1): 1-51

Bergquist, P.R. & Wells, R.J. 1983. Chemotaxonomy of the Porifera: the development and current status of the field. pp. 1-50 in Scheuer, P. (ed.). Marine Natural Products. New York : Academic Press.

Cook, S.D.C. & Bergquist, P.R. 2002. Family Thorectidae Bergquist, 1978. pp. 1028-1050 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1.

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