Polycarpa procera (Sluiter, 1885) Styela procera Sluiter 1885, p 196. Polycarpa procera: Kott 1985, p 196 and synonymy. Distribution Previously recorded (see Kott 1985): Western Australia (Cape Jaubert, Shark Bay, Cockburn Sound); South Australia (Upper Spencer Gulf); Victoria (Ninety Mile Beach, Bass Strait, Warnambool); New South Wales (Byron Bay); Queensland (Maroochydore, Hervey Bay, Gladstone, southern Great Barrier Reef, Innisfail); Indonesia, Singapore, Sri Lanka, Japan. New records: Queensland (17.165–17.935 ° S, 146.535–146.8 ° E, 35–68 m). Remarks The species is plentiful in inter-reefal locations in northeastern Queensland and a wide range in the Indo-West Pacific between Japan in the north to Sri Lanka and around the southern coast of the Australian continent. The species range supports the view that the Australian continental shelf acts as a bridge for gene flow between the tropics and temperate regions. Externally the species resembles Polycarpa chinensis (Tokioka, 1967) which has a similar range and habit to the present species. Both have a test brittle with embedded sand, more or less sessile apertures, rootlets on the ventral surface and the gut usually forming a simple arc between the posterior oesophagus to the base of the atrial aperture. However, the branchial sac of P. procera has distinct folds with up to 26 internal longitudinal vessels on each fold and at least seven, but sometimes many more between the folds; and it lacks the dorsal gonads and has lobes only on one lip of the bilabiate anal border. Polycarpa chinensis has dorsal gonads as well as ventral ones, both lips of the anal border are lobed, and its branchial folds are low, each having only four or five vessels and only one or two vessels are between the folds (see Kott 1985). These two species are difficult to distinguish externally and often are sympatric.

Published as part of Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), pp. 169-234 in Journal of Natural History 40 (3 - 4) on pages 218-219, DOI: 10.1080/00222930600621601, http://zenodo.org/record/5232431