ASCIDIIDAE Adams and Adams, 1858

Kott, Patricia, 2009, Taxonomic revision of Ascidiacea (Tunicata) from the upper continental slope off north-western Australia, Journal of Natural History 43 (31 - 32), pp. 1947-1986 : 1966

Family ASCIDIIDAE Adams and Adams, 1858

Type genus: Ascidia Linnaeus 1767 .

The family is relatively uniform, the large phlebobranch species having smooth, thick, firm, gelatinous and slightly translucent test, smooth on the outer surface and usually lacking epibionts or adhering particles. Branchial tentacles are simple and a large flat branchial sac has regular rows of rectangular stigmata and numerous uninterrupted internal longitudinal branchial vessels held away from the perforated pharyngeal wall by papillae. The gut, with gonads enclosed in its primary loop, is embedded in the left pallial body wall alongside the pharynx. A large branching tubular ovary and a mass of testis follicles are crowded in the gut loop.

Only two of the genera ( Ascidia and Phallusia ) in this family are even moderately speciose. The difference between them is associated with their size, Phallusia spp. being particularly large solitary individuals, and often vertical, fixed in sediments by the posterior end of the body. The dorsal ganglion and gland are about one-third to a half of the way down the body, separated from the opening of the gland on the dorsal tubercle (which remains just behind the ring of branchial tentacle at the anterior end of the body). This separation is compensated for by the multiple openings into the atrial cavity along the length of the neural duct. This character also occurs in some Ascidia spp. and may be associated with the size of the individuals rather then being a character of the genus.

Ascidia spp. usually are smaller individuals, often fixed to the substrate by the whole or part of the left side of the body and usually (though not always) with the dorsal gland and ganglion near the dorsal tubercle.

Both Ascidia and Phallusia are commonly recorded from the tropical Indo-west Pacific. Nevertheless, in the present collection the family is represented by only two species, one from each of these genera, namely Ascidia conifera , a species recorded on a few previous occasions from deeper continental shelf waters, and Phallusia millari , a commonly recorded species in the tropical Indo-west Pacific.