Herdmania grandis ( Heller, 1878 )

Kott, Patricia, 2008, Ascidiacea (Tunicata) from deep waters of the continental shelf of Western Australia, Journal of Natural History 42 (15 - 16), pp. 1103-1217 : 1206-1207

Herdmania grandis ( Heller, 1878)

Cynthia grandis Heller 1878, p. 15 .

Herdmania grandis: Kott 2002b, p. 363 and synonymy.

Distribution

Previously recorded (see Kott 2002): Western Australia ( Port Hedland , Cockburn Sound, Geraldton, Albany); South Australia ( Port Naorlinga ); Tasmania (Burnie); Victoria (Bass Strait); New South Wales (Ulladulla, Woolongong, Shell Harbour, Arrawarra, Byron Bay ), Queensland ( Tweed River , Moreton Bay, Mooloolaba, Low Is., Cairns, Murdoch Point); Papua New Guinea. New records: Western Australia CSIRO SS10 / 05 (Lancelin, Stn 76, 100 m, 1.12.05, QMG328432; Jurien Bay , Stn 83, 113 m, 02.12.05, QM G328150 ) .

Description

The new records are of three specimens to 10 cm long and about 5 cm depth. The apertures, on short, horizontal siphons at opposite ends of the upper surface, are directed away from each other. The test on the ventral surface of the body is produced into a thick beard of sand-encrusted roots. Otherwise the cream-coloured test is tough, leathery but flexible, even flaccid. The dorsal tubercle has a convoluted spiral split. The branchial sac has seven relatively narrow folds on each side. Longitudinal muscle bands from each siphon overlap over the upper half of the body but break into fine bands forming a mesh over the lower half of the body. Tonguelike flaps around the internal opening of the atrial siphon appear to be homologous with an atrial velum and have not previously been reported. The gonads are deeply embedded in the body wall, and consist of a thick tubular ovary with clumps of male follicles along the sides and sometimes over the surface. The gonoducal openings, which consist of a male opening lying on top of the oviducal opening, are deeply embedded in an endocarp like thickening of the body wall. Dense clumps of liver diverticulae lie in a row along the gut in the pyloric region. The anal rim is deeply divided into four leaf-like lobes.

Remarks

These large, flaccid individuals differ from previously described specimens only in the anal lobes. These are simple and leaf-like in the present specimen but appear to be smaller, less regular and sometimes subdivided in previously described specimens (see Kott 2002, Figure 2D–G ). The gonoducal openings, the dorsal tubercle and the form of the gonads are similar in all recorded individuals. It is the simple gonoducal openings and the form of the gonads that separates the species from others in this genus.

The newly recorded location on the western Australian coast is well within the known geographic range of this species, although the depth is greater than formerly known for the species. The known range is from around almost the whole of the Australian coast and from Papua New Guinea. It has not been reported from other locations in the western Pacific and it appears to be an indigenous species, rather than an introduction as Hartmeyer and Michaelsen (1928) had suggested. The most closely related species to the present one is Herdmania pallida ( Heller, 1878) which has similar gonads and simple gonoducal openings at the distal end of the ovary which lack the protective hood (found in H. momus and related species). Herdmania pallida has a much wider geographic range than the present species, its records being pan-tropical in all oceans (see Kott 2002) and it is distinguished from the present species by its short muscles confined to the upper part of the body, a simple double spiral rather than a convoluted slit on the dorsal tubercle, a single clump of liver lobes along the pyloric region of the gut (rather than a number of discrete clumps) and a smooth anal border.

Figures

Figure 2. Eudistoma convocatum sp. nov. (QM G328114): A, colony; B, zooid. Pseudodiazona longigona:(QM G328066) C, colony, with two small accessory lobes and sandfilled pharynges evident in some parts of the surface; D, thorax and abdomen; E, posterior abdomen with gonads. Scales: A, 5 cm; B, D, E, 1.0 mm; C, 5 cm.