Pseudodistoma australe Kott, 1957

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 191-192

Pseudodistoma australe Kott, 1957

Pseudodistoma australis Kott 1957, p 101 .

Pseudodistoma australe: Kott 1992a, p 428 and synonymy; 2003, p 1625 [not 1985 (sic) = 1992a].

Distribution

Previously recorded (see Kott 2003): Western Australia (Exmouth Gulf to Cockburn Sound); South Australia (Great Australian Bight, Cape Jaffa); Victoria ( Port Phillip Heads ); Queensland (Swain Reefs). New record : Tasmania ( Port Davey , 8–10 m, SAM E3231 ) .

Description

The colony is soft and translucent, its upper surface expanded into four short conical lobes like a crown. It converges slightly toward the base, where it appears to have been fixed to a wide, flat surface about 4 cm in diameter. Zooids extend up the colony parallel to one another and the independently opening six-lobed apertures are around the outside of the terminal lobes. Thorax and abdomen are, together, relatively short. Three rows, each of about 12 branchial stigmata, are in each half row and a short gut loop with a smooth-walled stomach is about halfway down the short abdomen. The posterior abdomen is very long, with strong bands of muscles along each side. Gonads were not detected in the newly recorded colonies, which appear to be in a vegetative stage, although there is a large embryo in the brood pouch (at the postero-dorsal end of the thorax) in a few of the zooids.

Remarks

These gelatinous, translucent rose-coloured colonies with a thick, soft stalk consisting of one or more terminal lobes, are characteristic of this wide-ranging apparently indigenous species. The new record is the most southern location known and confirms its wide range, often from temperate localities albeit extending into the tropics on both sides of the continent.