Herdmania

1928: 441

Distribution Previously Recorded. Western Australia (Geraldton to Albany, Hartmeyer & Michaelsen, 1928; Kott, 1952, 1972 b, 1985). South Australia (Millar, 1960, 1963, 1966; Kott, 1976). New South Wales (Heller, 1878; Herdman, 1882, 1899; von Drasche, 1884; Kott, 1952, 1985). Queensland (Moreton Bay to Cairns, Hastings, 1931; Kott, 1952, 1966, 1964). Papua New Guinea (Monniot & Monniot 2001) Examined Material. Western Australia (Port Hedland WAM Z 11766 / 1179.83; Cockburn Sound QM G 11896, WAM Z 11772 / 1180.83 Z 11774 / 1189.83 Z 11775 / 115.72 Z 11778 / 591.84 Z 11780 / 1181.83 Z 11781 / 756.82 Z 11782 / 1182.83 Z 11783 / 233.82 Z 11784 / 232.82), South Australia (Port Naorlunga, QM G 9318), Tasmania (Burnie, QM GH 4691), Victoria (Bass Strait, QM GH 2210), New South Wales (South Ulladulla QM G 8578; Woolongong, QM GH 5759; Shell Harbour AM Y 1814; Arrawarra, QM GH 2248; Byron Bay, QM G 308514). Queensland (Tweed River, QM G 308523; Moreton Bay, QM G 4928 G 5146 G 5166 G 8569 GH 377; Mooloolaba, QM GH 2349 GH 2200; off Murdoch Point, QM GH 769). Hartmeyer & Michaelsen (1928) believed that the forms of H. momus occurring in Australia (ff. grandis, galei, pallida) owed their wide geographical range to transport by ships. For instance, f. grandis, previously known from Port Jackson could have been transported to the south-western Australian coast in that way. However, H. grandis is now known to occur around the whole Australian coast (see Kott, 1985 and new records, below) and most likely is part of the indigenous fauna. Description The largest known species of Herdmania, some specimens being up to 16 cm or more in maximum dimension. Test tough, leathery, wrinkled and opaque. Smaller individuals to 2 cm also have opaque test. Lower half of body, often less wrinkled than upper half, sometimes sandy and may be embedded in sediments. Epibionts including other ascidians, often on outside of test. One specimen (QM GH 2210) has sand embedded in the test, making it hard and relatively brittle. Short cylindrical siphons originate close together in middle of upper surface and diverge from one another, or branchial siphon almost horizontal and atrial siphon vertical. Characteristic Herdmania spines crowded in body wall, especially long in posterior end and shorter anteriorly. Crowded spines in siphons aligned longitudinally. In contracted body wall spines, crowded into calcareous felt-work, sometimes lie parallel to one another. Circular muscles are around each siphon and its base. About 30 (individuals 2 cm long) to 50 (individuals from 4 cm long) strong longitudinal muscle bands on each side of the body radiate from atrial and branchial siphons and cross one another (the atrial muscles inside the branchial ones) on the sides of body, to create a meshwork of crowded muscles over whole body when contracted. In all specimens, muscles branch in lower half of body and form almost continuous layer over gut loop and gonads. Dorsal tubercle large, hemispherical cushion, usually filling anterior part of peritubercular area which has a narrow tongue-shaped extension projecting posteriorly in line with dorsal lamina. In smaller (2 cm: QM G 308523) specimens opening of neural duct is a long slit undulating around circumference of dorsal tubercle with its ends turned in, the gap between them directed anteriorly. In larger specimens the slit is more convoluted, covering whole surface of tubercle. Dorsal lamina narrow, extending through centre of circular area delimited on each side by a deeply curved dorsal branchial fold. Rather fleshy and very pointed languets are on the edge of the dorsal lamina. From six (small specimens to 4 cm: QM G 308523, GH 2200; AM Y 1814) to 12 (individuals to 10 cm or more) internal longitudinal vessels on flat area between dorsal fold on each side and short dorsal lamina converge at each end. From ten to 13 broad deeply curved, branchial folds on each side lie flat, folded up toward dorsum, ventral surface wider than dorsal surface of fold. Number of folds does not seem to be correlated with size, a specimen of 4 cm (QM GH 769) having ten folds on each side, and one of 2 cm (QM G 308523) having 11. Up to 23 internal longitudinal vessels on wider folds but only two or three in interspace. Gut loop and gonads embedded deeply in body wall in most larger specimens, although often gonads were not detected, suggesting individuals might be senescent. Anal border has two or three regular pointed lobes with lobed or scalloped margins, or irregular branched lobes or is sometimes almost smooth (QM G 8578 GH 2248). Testis follicles either in patches over each side of, or all over, upper surface of long, tubular, straight to slightly sinuous ovary deeply embedded in body wall alongside distal limb of gut loop. Oviducal opening large, sometimes slightly indented. Common vas deferens extends along top of ovary, opening on short inconspicuous papilla near female opening. Specimen 2 cm long from Shell Harbour (AM Y 1814), a juvenile without gonads, identifiable with present species by its slightly convoluted circular slit on dorsal tubercle, six internal longitudinal vessels between dorsal lamina and left dorsal fold, 11 branchial folds on each side and long body muscles extending down over gut and gonads. Remarks As well as becoming larger than those of other known species, individuals of this indigenous species, even small specimens, are distinguished from others by their tough opaque test, large dorsal tubercle with convoluted slit, six or more internal longitudinal vessels between the short dorsal lamina and deeply curved dorsal fold, long and straight or almost straight ovarian tube with only occasional irregular, shallow undulations, testis follicles in clumps or crowded in an uninterrupted mass on the upper surface of the ovary (along each side or completely covering it), common vas deferens opening on a small papilla on top of the short oviduct, oviducal opening wide (without a hood) and long, strong radial muscles from each siphon crossing each other over the whole of each side of the body. This last character is unique, other species having radial muscles that terminate at the anterior limits of the gut loop (on the left) and the gonad (on the right). Possibly the contraction of these muscles in the present species cause the gonad on the left to be tightly associated with the distal limb of the gut loop. Further, the number, strength and length of the muscles in this species effects such strong contraction that spines are often drawn together in parallel to form a hard layer over the whole of the body wall.