Pyura tasmanensis Kott, 1985

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 224

Pyura tasmanensis Kott, 1985

Pyura tasmanensis Kott 1985, p 331 .

Distribution

Previously recorded (see Kott 1985): Tasmania (Ralph’s Bay, Roches Beach , Tasman Head , Port Davey ). New records: Tasmania ( Port Davey , 3–25 m, SAM E2875 ; Tasmanian Canyons (Big Horseshoe—Broken Reef, 115 m )) .

Description

The newly recorded specimens do not appear to be in aggregates. In preservation both specimens are almost spherical with a wrinkled test. Apertures are close together on the upper surface, although the dorsal lamina is moderately long. Branchial tentacles usually are long, with short primary and smaller secondary and tertiary branches, although the specimen from the Tasmanian Canyons has short, inconspicuous tentacles without secondary or tertiary branches. Siphons are lined with long overlapping siphonal spines. Six folds are on each side of the branchial sac with up to 28 internal longitudinal vessels per fold and up to 12 between. Crowded endocarps are on the descending limb of the gut loop and on the gonads. A conspicuous green liver diverticulum branches off the gut in the pyloric region. Each of the two lips of the anal border is divided into two.

Remarks

The species is distinguished from P. stolonifera by its long dorsal lamina and the more numerous internal longitudinal vessels between the folds. The siphonal spines of P. stolonifera are seldom more than 0.1 mm long, while those of P. tasmanensis sometimes are as much as 0.2 mm (see Kott 1985) and the gut loop of the latter species has a narrower curved gut loop with up to 15 pairs of polycarp sacs. Pyura stolonifera has a more open gut loop with only about eight pairs of hermaphrodite gonads.