Family FLUSTRELLIDRIDAE Bassler, 1953

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• Flustrellidridae Bassler, 1953.

Introduction

The family Flustrellidridae was introduced by Bassler (1953) for the genus Flustrellidra and some other carnose ctenostomes, and was revised by Cook (1964) to include Flustrellidra, Elzerina and Bockiella .

The family is characterised by the regular patterning of autozooids and surrounding kenozooids, each of which frequently has the cuticular frontal wall extended to form a thickened spine. The autozooid orifice is also thickened to produce an operculum-like lower lip.

Flustrellidra hispida has large, encrusting autozooids with lophophores bearing as many as 35 tentacles. Its larvae are bivalved, with a vestigial gut (Prenant & Bobin, 1956). Flustrellidra has colonies which often encrust algae, or are erect and lobed; its species are widely distributed in the northern hemisphere, particularly in arctic and boreal waters.

In Australia, the family is represented by two genera with erect, branched colonies, Elzerina and Bockiella. E. blainvillii was one of the first species to be described from Australia, by Lamouroux (1816), and his figured specimen is still extant. Colonies have dichotomous branches, up to 50 mm in height; marked by constricted kenozooids forming joints, analogous to those of some cheilostome genera, such as Cellaria in appearance and function. Each autozooid is surrounded by a series of kenozooids, which are large and smooth in E. blainvillii, and small and spiny in E.cylindrica. Both species have up to 23 tentacles. Elzerina occurs from shallow shelf waters. E. blainvillii is found round all Australian coasts, and from South Africa; E.cylindrica has been reported only from Victoria. Species of Bockiella have erect colonies with less regular patterning of branches, and kenozooids which have no spines. The type species, B. angusta, occurs from fairly deep waters, from Japan to Bali (135-752 metres), but the only Australian species, B. robusta, grows on algae in shallow shelf waters from New South Wales (Cook 1964).

Diagnosis

Colony encrusting or erect, fleshy, with thickened cuticle. Autozooids generally relatively large, the orificial region either papilliform, or with an operculum-like flap formed from the proximal part of a thickened, bilabiate orifice. Kenozooids always present, with a definite position in relation to autozooids; smooth-surfaced or spinose. Several embryos brooded in one zooid, bivalved larvae produced.

General References

Bassler, R.S. 1953. Bryozoa. Treatise on Invertebrate Paleontology, Part G, Moore, R.C., (editor). Lawrence, Kansas : Geological Society of America pp. G1-G253.

Cook, P.L. 1964. Notes on the Flustrellidridae (Polyzoa, Ctenostomata). Annals and Magazine of Natural History 13 7: 279-300

Lamouroux, J.V.F. 1816. Histoire des Polypiers Coralligènes flexibles vulgairement nommés Zoophytes. Caen : Poisson i-ixxxiv, 1-560, pls 1-19.

Prenant, M., & Bobin, G. 1956. Bryozoaires, premiere partie, Entoproctes, Phylactolèmes, Ctenostomes. Faune de France, 60. Paris : Fédération Française des sociétés de sciences naturelles pp. 1-398.

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