Family IANTHELLIDAE Hyatt, 1875

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Introduction

Among the family Ianthellidae Hyatt, 1875, lobate and fan-shaped, stalked growth forms are common. Pigmentation ranges from typically verongid sulphur yellow, deep orange to deep purple, and all show the characteristic oxidation reaction upon damage or death, eventually turning deep purple. The fibre skeleton, where present, is reticulate and frequently compressed into two dimensions, radiating from the contracted basal attachment. Fibres may attain large sizes, particularly towards the base of the sponge, and contain cellular elements in distinctive concentric annuli occurring mainly in the bark component of each fibre. Choanocyte chambers are large and eurypylous, sac-shaped, varying between genera from simply elongate to occasionally branched.

Three genera are recognised in the family, all restricted to relatively shallow waters (Hartman 1982). All three genera are represented in the Australian fauna (Bergquist 1980; Bergquist & Kelly-Borges 1995).

Biochemical characteristics of Ianthellidae are similar to those of the Aplysinidae with respect to the occurrence of brominated metabolites. No aplystane sterols have yet been recorded in any species of Ianthellidae, whereas these sterols characterise the Aplysinidae and Druinellidae, which are almost identical in their major biochemical characteristics (Bergquist 1980).

The Ianthellidae (which includes Bajalidae Lévi, 1958 in synonymy) is reviewed in Bergquist (1980), and the genus Ianthella in Bergquist & Kelly-Borges (1995).

Diagnosis

Verongida in which the fibre skeleton when present is strongly anastomosing, frequently compressed into two dimensions, and radiating from a contracted base of attachment. Fibres contain cellular elements in concentric annuli; these occur mainly in bark elements, but can also be dispersed in pith as well. The fibres are of typical construction for the order with bark and pith elements represented, neither component is emphasised. Individual fibres can attain great thickness, particularly towards the base of the sponge. The skeleton makes up the major bulk of the sponge. A thick firm skin-like dermis is common to all species as is the inclusion of spherulous cells among the secretory cell content. The choanocyte chambers are large, and sac-shaped (Ianthella, Hexadella), to slightly ovate-elongate and occasionally branched (Anomoianthella). Colour in life ranges from sulphur yellow through deep orange, blue to deep purple or purple brown. All species show a characteristic oxidation reaction upon damage or death, and reach a final deep purple colouration. Soft tissue pigmentation is always uniform throughout the sponge. Biochemical characteristics are similar to those of the Aplysinidae, Pseudoceratinidae and Aplysinellidae with respect to the occurrence of brominated metabolites but highly complex variants of these molecules occur in the Ianthellidae. No aplystane sterols are known from any species of Ianthellidae.

ID Keys

KEY TO GENERA
(1) Fibre skeleton present ------------------------------------------------------------------------------------------------------- 2
Fibre skeleton absent ----------------------------------------------------------------------------------------------- Hexadella

(2) Fibre reticulation two dimensional sometimes with fasciculate extensions vertical to that plane ------- Ianthella
Fibre reticulation anastomosing in three dimensions ---------------------------------------------------- Anomoianthella

Diagnosis References

Bergquist, P.R. & Cook, S.D.C. 2002. Family Ianthellidae Hyatt, 1875. pp. 1089-1093 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. [1089]

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. & Cook, S.D.C. 2002. Family Ianthellidae Hyatt, 1875. pp. 1089-1093 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.

Bergquist, P.R. & Kelly-Borges, M. 1995. Systematics and biogeography of the genus Ianthella (Demospongiae: Verongida: Ianthellidae) in the South-west Pacific. The Beagle, Records of the Museums and Art Galleries of the Northern Territory 12: 151-176

Hartman, W.D. 1982. Porifera. pp. 640-666 in Parker, S.P. (ed.). Synopsis and Classification of Living Organisms. New York : McGraw-Hill Vol. 1.

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