Family TETRAPLARIIDAE Harmer, 1957

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Introduction

The family Tetraplariidae was introduced by Harmer (1957) for Tetraplaria Tenison Woods (1879). Harmer regarded Tetraplaria as a senior synonym of the genera Bigemellaria, Diploecium, Pollaploecium and Arborella. Gordon (1989) has discussed the validity of the name, which may be a junior synonym of the discarded genus, Onchopora. For the present, he advises that this problem be ignored, and the name Tetraplaria is therefore used here.The genus Tetraplaria is characterised by erect, jointed colonies, with internodes composed of pairs of zooids opposite each other. The autozooids are pear-shaped, produced proximally, with a swollen, cryptocystidean frontal shield, with numerous pseudopores. Ontogenetic thickening may produce tubercles between the pores. The autozooid orifice is terminal and sinuate, with minute condyles; spines are absent, but the orifice is surrounded by a raised, thickened rim of calcification. The internodes are composed of from one to 11 pairs of zooids, depending upon the species; the joints are tubular and cuticular. Avicularia are absent and some species have small, hyperstomial, porous ovicells, which are immersed in the next distal zooid. Other species have interior ovisacs, and enlarged fertile zooids.The type species of Tetraplaria is a Tertiary fossil from Victoria, T. australis Tenison Woods, (1879). Wass & Yoo (1983) considered that this species also occurred from the Great Australian Bight, together with another Tertiary species, T. pedunculata (MacGillivray, 1895). Harmer (1957) described two species from Queensland and the Torres Strait originally introduced by Haswell (1881), T. ventricosa and T. immersa. All these species are very similar to one another, but whereas T. ventricosa possesses ovicells, both T. immersa and T. australis do not. The fertile zooids of T. australis illustrated by Wass & Yoo (1983) are twice the size of the autozooids, and have a large, wide, dimorphic orifice. T. ventricosa and T. immersa occur in shallow water; Ryland (1974) found yellowish colonies of T. ventricosa conspicuous, with Nellia, on the shaded side of large, sublittoral boulders in Queensland. Wass & Yoo (1983) reported T. australis and T. pedunculata from deeper water, down to 143 metres.

Eocene fossils of Tetraplaria are known from India (Taylor 1993). In Australia, fossils are moderately common in the Miocene and Oligocene of Victoria.

Diagnosis

Colony erect, thinly calcified at first, arising from a very small, encrusting base, and anchored by numerous, long, cuticular rhizoids. Branches nodal, formed by apposed paired of zooids, nodes cuticular. Zooids elongated proximally, frontal lepralioid, with numerous pseudopores, and nearly terminal, sinuate orifice. Avicularia absent. Brooding in interior ovisacs of enlarged zooids with dimorphic orifices, or in large, porous, hyperstomial ovicells.

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

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

Haswell, W.A. 1881. On some Polyzoa from the Queensland coast. Proceedings of the Linnean Society of New South Wales 5: 33-44

Macgillivray, P.H. 1895. A monograph of the Tertiary Polyzoa of Victoria. Transactions of the Royal Society of Victoria ns 4: 1-166

Ryland, J.S. 1974. Bryozoa in the Great Barrier Reef Province. Proceedings of the 2nd International Coral Reef Symposium 1: 341-348

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

Tenison-Woods, J.E. 1879. On some Australian Tertiary fossil corals and Polyzoa. Proceedings of the Royal Society of New South Wales 12: 57-61

Wass, R.E. & Yoo, J.J. 1983. Cheilostome Bryozoa from the Southern Australian Continental Shelf. Australian Journal of Marine and Freshwater Research 34: 303-354

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