Family THEONELLIDAE Lendenfeld, 1903

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Introduction

Theonellidae Lendenfeld, 1903 are with tetraclone choanosomal desmas and phyllo- to discotriaenes as ectosomal spicules. They are generally massive, cup-shaped, vase-shaped or cylindrical sponges with a narrow central cavity. Their megascleres consist of fused desmas, including tri- or tetracrepidial desmas (Hooper & Wiedenmayer 1994: fig. 58) having four arms without triaenose symmetry, and free megascleres that include phyllo-, disco- or dichotriaenes (Hooper & Wiedenmayer 1994: figs 36–43). Microscleres are microxeas (Hooper & Wiedenmayer 1994: fig. 105), microstrongyles (Hooper & Wiedenmayer 1994: fig. 106), amphiasters or spirasters (Hooper & Wiedenmayer 1994: figs 118, 120).

Five living genera are included in this family by the most recent revision (Pisera & Lévi 2002), widely distributed in tropical and warm-temperate seas at depths ranging from 30–800 m (Hartman 1982). Two of the seven genera are represented in the Australian fauna.

Although the family is included in the polyphyletic order Lithistida, it has apparent affinities with the Hadromerida. Synonyms include Kaliapsidae de Laubenfels, 1936; Jereidae de Laubenfels, 1955; Discodermiidae Schrammen, 1910; and Phymatellidae Schrammen, 1910.

Wilson (1925), Brien et al. (1973), Hartman (1982) and Pisera & Lévi (2002) review the Theonellidae.

Diagnosis

Polymorphic; choanosomal spicules are tetraclone desmas; ectosomal spicules are phyllo- to discotriaenes; microscleres are spinose microrhabds and/or microxeas, and streptasters, and/ or pseudospherasters which are believed to be derivatives of acanthorhabds or amphiasters; large choanosomal oxeas may be present.

ID Keys

KEY TO EXTANT GENERA
(1) Ectosomal spicules exclusively discotriaenes, microscleres are acanthorhabds and acanthoxeas ---------------- 2
Ectosomal spicules include phyllotriaenes ------------------------------------------------------------------------------------- 3

(2) Ectosomal spicules discotriaenes, desmas are typical tetraclones, microscleres are acanthoxeas and
acanthorhabds --------------------------------------------------------------------------------------------------- Discodermia
Ectosomal spicules discotriaenes, desmas are tetralophs, microscleres are acanthostrongyles ---------------------------------------------------------------------------------------------------------------- Siliquariaspongia

(3) Ectosomal spicules phyllotriaenes, microscleres are pseudospherasters -------------------------------- Manihinea
Ectosomal phyllotriaenes to discotriaenes, microscleres are acanthorhabds --------------------------------- Theonella
Ectosomal disco- to phyllotriaenes, microscleres are streptasters and acanthorhabds ------------------ Racodiscula

Diagnosis References

Pisera, A. & Lévi, C. 2002. Family Theonellidae Lendenfeld, 1903. pp. 327-337 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. [327]

General References

Brien, P., Lévi, C., Sarà, M., Tuzet, O. & Vacelet, J. 1973. Spongiaires. pp. 1-716 485 figs in Grassé, P.P. (ed.). Traité de Zoologie. Anatomie, Systématique, Biologie. Paris : Masson et Cie Vol. 3(1).

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.

Pisera, A. & Lévi, C. 2002. Family Theonellidae Lendenfeld, 1903. pp. 327-337 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.

Wilson, H.V. 1925. Silicious and horny sponges collected by the U.S. Fisheries steamer Albatross during the Philippine Expedition, 1907–10. In Contributions to the biology of the Philippine Archipelago and adjacent regions. Bulletin of the United States National Museum 100(2/4): i-vii 273-532 pls 37-52

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