Family STOMOZOIDAE

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Introduction

The family Stomozoidae Kott, 1990 is small, containing only three known species, two in Australia and one with a cosmopolitan distribution (Kott 1990). The family is distinguished by the fringed lobes that surround each separately opening aperture. These lobes alternate with conspicuous pigment spots, similar to those known in other aplousobranch and phlebobranch ascidians. A siphonal velum projects forwards inside the lobes to form the actual branchial opening. Small gonads with only a one- or two-egg ovary are in the moderately long gut loop. Vascular stolons of moderate length, sometimes branching, project down into the basal test from the embedded zooids, but they do not appear to have terminal ampullae as in Clavelinidae (which is further distinguished by its smooth-rimmed apertures). Longitudinal muscles extend along each side of the thorax and abdomen but not onto the vascular stolon as in Sigillina Savigny, 1816 (Holozoidae). The larvae have large triradially arranged adhesive organs (as in Clavelinidae). Nevertheless, the family appears to be most closely related to Polycitoridae (see Kott 1990).

Although they are not inconspicuous, forming fleshy cushion-like colonies, species of this genus are seldom recorded, and possibly their preferred habitat has not yet been located.

General References

Kott, P. 1990. The Australian Ascidiacea Pt 2, Aplousobranchia (1). Memoirs of the Queensland Museum 29(1): 1-266

Savigny, J.C. 1816. Recherches anatomiques sur les ascidies composées et sur les ascidies simples—Système de la classe des Ascidies pp. 1–239. In Mémoires sur les Animaux sans Vertèbres, Pt 2. Paris : G. Dufour.

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