Family SAVIGNYELLIDAE Levinsen, 1909

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Introduction

The family Savignyellidae was introduced by Levinsen (1909) for Savignyella lafontii (Audouin), and, as recognised here, is characterised by delicate, inconspicuous, branching colonies (up to 45 mm tall), composed of uniserial chains of zooids. Erect branches arise from encrusting, creeping chains of uniserial zooids, and each unizooidal segment is separated from neighbours by tiny, uncalcified joints. Each zooid is club or vase-shaped, tapering proximally to the joint. The frontal shield is subhemispherical, has numerous small pores, and is covered by a thin, closely applied membrane; the dorsolateral wall is smooth. The orifice is relatively large and nearly circular, and brooding zooids have an ovicell. Ovicells have numerous small ectooecial perforations in Savignyella, two relatively large entooecial pores in Halysisis. Savignyella alone has an oral avicularium and oral spines. The avicularium is median, originating from a tiny, lateral septular pore, but not occurring on every zooid. The spines number 4-6 and are unjointed.

The family dates from the Lower Eocene; its affinities are not certain (Taylor, 1993). The occurrence of gymnocystal strips laterally, delimiting shallow pore chambers with septular pores in Halysisis, indicates an affinity with the Catenicelloidea.

Savignyella lafontii (Audouin) is widespread in warm, shallow waters, and is circumtropical, including the Mediterranean, the IndoPacific and Hawaii (Gordon 1989). In Australia it occurs in north Queensland (Hastings 1932; Hall 1984). In life, colonies are brick-red to brown and there are 17-19 tentacles (Winston, 1982). S. lafontii frequently occurs with other erect, delicate bryozoans, on algae, sponges or other bryozoans, either sparsely, or as a turf on pilings and other substrata. It is known as a fossil from the Miocene of Central America and the Gulf, and from Indonesia (Lagaaij 1968).

Halysisis has not been recorded from Australia, but it is known from Indonesia, including Timor (Harmer, 1957), and will very probably be encountered along the northern coast and in Torres Strait in the future.

Diagnosis

Colony erect, thinly calcified, with delicate branches, arising from a creeping base. Zooids uniserial, alternating with cuticular joints, elongated and tapering proximally, with a porous gymnocystal frontal and terminal orifice. Sessile avicularia and oral spines sometimes present. Ovicells small, porous.

General References

Gordon, D.P. 1989. The marine fauna of New Zealand: Bryozoa: Gymnolaemata (Cheilostomida Ascophorina) from the western south Island continental shelf and slope. New Zealand Oceanographic Institute Memoir 97: 1-158

Hall, D.N. 1984. Cheilostome Bryozoa from Townsville Harbour and Picnic Bay, North Queensland. Proceedings of the Royal Society of Queensland 95: 57-70

Harmer, S.F. 1957. The Polyzoa of the Siboga Expedition. Part 4. Cheilostomata Ascophora II. Siboga-Expéditie Report 28D: 641-1147

Hastings, A.B. 1932. The Polyzoa, with a note on an associated hydroid. Scientific Reports of the Great Barrier Reef Expedition 1928-1929 4(12): 399-458

Lagaaij, R. 1968. First fossil finds of six genera of Bryozoa Cheilostomata. (Proceedings of the First International Conference on Bryozoa; Annoscia,E, ). Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 108: 345-360

Levinsen, G.M.R. 1909. Morphological and systematic studies on the cheilostomatous Bryozoa. Copenhagen : Nationale Forfatteres Forlag 431 pp.

Taylor, P.D. 1993. Bryozoa. pp. 465-489 in Benton, M.J. (ed.). The Fossil Record 2. London & New York : Chapman & Hall 845 pp.

Winston, J.E. 1982. Marine bryozoans (Ectoprocta) of the Indian River area, Florida. Bulletin of the American Museum of Natural History 173: 99-176

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