Family PROTOPOLYCLINIDAE

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Introduction

Zooids of the family Protopolyclinidae Kott, 1992 are divided into thorax, abdomen and posterior abdomen. The gonads are in the posterior abdomen. Both branchial and atrial openings are 6-lobed. The family contains species with either embedded zooids or zooids joined to one another only at the base. When embedded, the zooids are arranged in an orderly way, usually in systems but these are never cloacal systems., Atrial apertures are directed away from the branchial apertures but they never open into internal cloacal chambers. The abdomen is relatively short, the stomach wall sometimes is folded, the gonads are bunched in the posterior abdomen and the anus opens about halfway up the large thorax. As in Polyclinum, internal branchial papillae-possibly vestiges of the internal longitudinal branchial vessels of Cionidae and Diazonidae-usually are present in the branchial sac, suggesting a direct relationship with the Diazonidae. However, larvae have diverged considerably from the small oviparous diazonid larvae. Eggs are fertilised in the distal end of the oviduct which appears to extend alongside the rectum in the posterior half of the branchial sac. The larvae resemble those of Polyclinidae with median stalked adhesive organs, median and lateral epidermal amullae, and lateral epidermal vesicles.

Three genera are known in the family. They are recorded infrequently, and only from the Southern Hemisphere. One of the three genera is indigenous to Australian waters, one is known also from the West Indian Ocean, and the third, Protopolyclinum Millar, 1960 is known from a single record from New Zealand.

General References

Kott, P. 1992. The Australian Ascidiacea Pt 3, Aplousobranchia (2). Memoirs of the Queensland Museum 32(2): 377-620

Millar, R.H. 1960. Ascidiacea. Discovery Reports 30: 1-160

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