Herdmania grandis ( Heller, 1878 )

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 225-226

Herdmania grandis ( Heller, 1878)

Cynthia grandis Heller 1878, p 15 .

Herdmania grandis: Kott 2002, p 363 and synonymy.

Distribution

Previously recorded (see Kott 2002): Western Australia (Geraldton to Albany); South Australia (Gulf St Vincent); Tasmania (Burnie); Victoria (Bass Strait); New South Wales ( South Ulladulla , Wollongong, Shell Harbour, Arrawarra, Byron Bay ); Queensland (Tweed River, Moreton Bay, Mooloolaba, off Murdoch Point, Cairns); Papua New Guinea. New records: Tasmania (Bass Strait; King I. Canyon, 348 m, QM G308809 ; Banks Strait, 168 m); Queensland (benthic fauna, 14.705–18.655 ° S, 145.375–147.075 ° E, 11–69 m) .

Description

A large specimen newly recorded from King I. Canyon has an opaque, leathery but flexible test with fine horizontal wrinkles and some irregular tags and processes on the lower half of a turnip-shaped body. The body wall is translucent despite the strong muscles that extend down each side to the endostyle. A horizontal S-shaped slit is on the dorsal tubercle with both horns turned in. Seven branchial folds are on each side. The atrial velum is divided into 16 rounded lappets. The gut loop is only slightly curved and compact clumps of liver lobes are on the gut loop. A long endocarp is on each side of the body, the one on the left curving around the ventral mid-line and covering the descending limb of the gut loop. Clumps of male follicles surround the ovarian tube. The male duct opens on a short projection from the surface of the distal end of the oviduct just behind the simple, sessile oviducal opening. The anal opening is bilabiate, and the margin of each lip is divided into conspicuous rounded lobes.

This specimen differs from others of this species in the absence of languets on the dorsal lamina and the relatively few branchial folds. These differences may be the result of isolation from other temperate populations; or it may be an aberrant individual. Smaller cushion-like specimens to about 2 cm long from Banks Strait and Bass Strait have the usual complex, convoluted slit on the dorsal tubercle. Up to 30 small specimens of the present species to 1–3 cm but occasionally to 6 cm occur at over 25% of the 88 benthic locations sampled on the continental shelf of north-eastern Queensland. Although gonads are not always present, these specimens have gonoducal openings, lobed anal border, and the numerous branchial folds characteristic of H. grandis .

Remarks

The large number of small specimens taken from the northeastern Queensland continental shelf in September and October 2003 suggest that the species may dominate the benthic communities there; and that settlement takes place in autumn in these waters. Although some variation is apparent in the number of branchial folds, the relatively straight ovarian tube, simple gonoducal openings that lack of associated membranes from the body wall, the lobed anal border, and the long muscles that extend over the whole body wall are consistent characters defining the species.