Family PORINIDAE D'Orbigny, 1852

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Introduction

The family Porinidae was introduced by d'Orbigny (1852) for fossil and Recent species, without any indication of a type genus. The complexities of the nomenclatorial history of this family were discussed by Gordon (1984), and further analysis was undertaken by Gordon & d'Hondt (1997).

The genus Porina has erect rod-shaped or flattened colonies with highly porous frontal shields. The genera Spiroporina Stoliczka and Haswellina Livingstone were considered to be synonymous with Porina by Gordon & d'Hondt (1997). The primary orifice is subcircular, with a sinus, which may be well or poorly developed, defined by a pair of condyles. As secondary calcification develops rapidly, the primary orifice is seen only at the growing ends of branches. Calcification surrounds the peristome, which may open at the colony surface, or project beyond the surface. A spiraminal tube extends from the interior of the peristome, just above the proximal edge of the primary orifice, and opens somewhat proximal to the secondary orifice. Small adventitious avicularia are concentrated near the rim of the secondary orifice. Ovicells are submerged in the secondary calcification, but often can be identified by a convexity on the calcification distal to the orifice. P. gracilis Lamarck has the zooids arranged alternately, and is widely distributed on the southern Australian continental margin. P. australiensis (Haswell) has verticillate rows of zooids. It has been reported from Queensland and from Western Australia by Marcus (1921), but the large number of other localities given by Harmer (1957) all require examination.

A second genus in the family, Haswelliporina, was described by Gordon & d'Hondt (1997), for material from New Caledonia. It is possible that this genus will also be found in the Australian region.

Collections of Porina have been made from water depths of less than 10 m down to a maximum of over 1200 m, for a locality off the east coast of Tasmania. Most records are from 40 to 150 m depth, but this also reflects the bias in samples available for study.

Several fossil species of Porina were described from the Tertiary of Victoria by MacGillivray (1895).

Diagnosis

Colony well- to massively calcified, erect, branched, arising from a small, encrusting base. Branches circular or flattened, zooids arranged in whorls. Primary orifice deeply immersed in a peristome which is not prominent, but is often surrounded by small avicularia at the surface. Proximal spiramen present. Ovicell completely immersed, with a dimorphic secondary orifice.

General References

D'Orbigny, A. 1852. Paléontologie Française, Terrains Crétacés, V, Bryozoaires. Paris : Victor Masson 185-472 pp.

Gordon, D.P. 1984. The marine fauna of New Zealand: Bryozoa: Gymnolaemata from the Kermadec Ridge. New Zealand Oceanographic Institute Memoir 91: 1-198

Gordon, D.P., & d'Hondt, J.-L. 1997. Bryozoa: Lepraliomorpha and other Ascophorina from New Caledonian waters. (Résultats des Campagnes MUSORSTOM, Vol. 18, Crosnier, A., ). Mémoires du Muséum national d'Histoire naturelle, Paris [1936-1950] 176: 9-124

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

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

Marcus, E. 1921. Results of Dr. E. Mjöbergs Scientific Expeditions to Australia 1910-1913, 24, Bryozoen. Kongliga Svenska Vetenskaps-Academiens Nya Handlingar, Stockholm 61(5): 1-34

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