Polycarpa viridis Herdman, 1880

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 : 1202-1205

Polycarpa viridis Herdman, 1880

Polycarpa viridis Herdman 1880, p. 74 . Kott 1985, p. 208 and synonymy. Polycarpa ovata Pizon 1908, p. 211 . Kott 1985, p. 82 and synonymy.

Distribution

Previously recorded (see Kott 1985): Western Australia (Cockburn Sound) ; South Australia (Great Australian Bight, Spencer Gulf , Gulf St Vincent); Victoria (Bass Strait) ; New South Wales (Cape Jervis, Port Jackson); Queensland ( Moreton Bay and north to Trinity Bay ). New records : Western Australia CSIRO SS10 /05 (Jurien Bay, Stn 83, 113 m, 2.12.05, QM G328155 seven specimens, G328422; Abrolhos , Stn 93, 112 m, 3.12.05, QM G328468 two specimens; Kalbarri, Stn 99, 262 m, 4.12.05, QM G328469 ; Kalbarri, Stn 102, 96– 98 m, 05.12.05, QM G328062 , G328467 three specimens; Zuytdorp, Stn 110, 106 m, 06.12.05, QM G328143 ) .

Description

Individuals are small (seldom more than 2 cm long) and oval with a variable amount of sand embedded in the thin test. Some specimens are sessile, attached basally to a mass of pebbles, others gradually reduce in diameter to a thick basal stalk, and several specimens have a short, narrow stalk from the posterior end of the body or a long, thin, irregular stalk from the postero-ventral quarter. Apertures are small and sessile, the branchial terminal and the atrial halfway along the dorsum. The preserved specimens have blackish-brown to beige test and body wall. The body wall is muscular with an external coat of crowded transverse muscles outside the longitudinal ones. The dorsal tubercle is a large, spongy cushion that fills the peritubercular V with a deep interrupted slit. Four narrow longitudinal branchial folds with crowded and prominent internal longitudinal vessels are on each side of the branchial sac. The stomach is elliptical, occupies about half of the ascending limb of the gut loop and has fine longitudinal folds lining its internal wall The pole of the gut loop curves tightly around a circular, flat-topped endocarp and then continues anteriorly as a long rectum that is about twice the length of the primary loop and terminates at the atrial aperture in an anal opening fringed with well-defined lobes. The number of short, oval polycarps embedded in the body wall is variable, sometimes being confined to the lower half of the body though some often extend into the secondary gut loop.

Remarks

Kott (1985) distinguished Polycarpa ovata Pizon, 1908 from Polycarpa viridis Herdman, 1880 by its very small vesicles in the body wall, and flask-shaped gonads with ducts opening on a small papillum at the dorsal end. Nevertheless, she refers to the variability of the gonads, a fact confirmed by gonads in the present specimens, which vary in numbers, shape, the extent to which they overlap, and in the degree to which they are embedded in the body wall. The size of the embedded vesicles, the shape of the body, black brown colour of the test and body wall and the amount of sand embedded in the test are also variable. The characters shared by the specimens assigned here to this species are sessile apertures, a spongy dorsal tubercle completely filling the peritubercular area with a deep sometimes interrupted slit, a tough branchial sac with stout internal longitudinal vessels, a single large flat-topped endocarp in the pole of the gut loop, an unusually long rectum (twice the length of the primary gut loop), rounded and moderately long anal lobes and small crowded polycarps embedded in the body wall. These characters are shared by P. viridis and P. ovata and represent a more compelling argument for synonymy than the variable characters formerly relied on to separate these species.

Although its junior synonym had been recorded from the tropical waters of the Queensland coast, the species appeared to have a primarily temperate geographic range. However the new records extend its known range in Western Australia from Cockburn Sound to Shark Bay.

Polycarpa flava and P. fungiformis are also black species although they have especially large conspicuous vesicles embedded in the body wall. The former also has its gonads deeply embedded and in the latter species the endocarp enclosed in the gut loop is irregular in outline rather than the circular, flat-topped mass found in the present species. Polycarpa pedunculata is a similar stalked species but the endocarp enclosed in the gut loop is elongate rather than circular, the stomach is long, occupying almost the whole of the proximal limb of the gut loop and the gonads tend to be longer than the oval-circular polycarps of the present species.

Sub-family POLYZOINAE

Stolonica aluta Kott, 1985

( Figures 15C, D )

Stolonica aluta Kott 1985, p. 233 ; 2003, p. 1642.

Distribution

Previously recorded (see Kott 2003): Western Australia (Dongara). New record: Western Australia CSIRO SS10 / 05 (Bald I., Stn 35, 200 m, 24.11.05, QM G328460 ) .

These specimens are as previously described for this species, which previously was known only from its type locality off Dongara and, with the new record from the south coast of Western Australia, its known range is extended to include the southwestern corner of the continent .

Description

Small upright oval zooids about 1 cm long are scattered amongst rubble to which they are firmly attached by a short, narrow stalk with irregular terminal root-like projections. The test is tough, creamish-white, without sand adhering to the smooth outer surface. The apertures are on short siphons and in these contracted specimens a small wart-like protrusion surrounds each opening. Posteriorly the body narrows to the stalk, which is hollow and contains an extension of the body wall. Connecting stolons were not detected in these specimens. The branchial aperture is terminal and the atrial aperture antero-dorsal. Long, simple branchial tentacles are at the base of the branchial siphon. The body wall is muscular with longitudinal bands beneath an external coat of transverse fibres. The branchial sac has three folds on each side of the body. A branchial formula on the left is E3(14)7(9)6DL. Up to four long, narrow stigmata are in each mesh, which is usually crossed by a parastigmatic vessel. The gut forms a loosely attached loop on the left. The stomach, occupying about half of the ascending limb of the primary loop, has longitudinal folds which become progressively shorter toward the distal end on the anterior (inner) margin which is extended out into a spur from which a conspicuous caecum curves into the pole of the gut loop. The intestine continues posteriorly as the descending limb of the primary gut loop before sharply turning anteriorly into the rectum, which extends to the atrial opening. The body wall has numerous small endocarps, especially crowded around the postero-ventral part of the body on the right and especially on the left side of the endostyle (beneath the ventral curve of the gut loop). Scattered amongst these endocarps are small male follicles with short vas deferens directed dorsally. These male follicles are especially numerous on the left. Ovaries were not detected in these specimens.

Remarks

It is an inconspicuous species, however, with a cryptic habitat amongst the rubble that it is attached to so firmly and it could be found to have a wider range. The tight curves of the gut loop and the crowded endocarps mixed with the male follicles are very likely the result of contraction of the body wall. Stolonica reducta has some

characters in common with the present species but its gonads are in a row along each side of the endostyle.

Family PYURIDAE Hartmeyer, 1908

Figures

Figure 15. Cnemidocarpa completa (QM G328141): A, external view; B, internal view, right side showing branchial sac cut away to display gonads. Stolonica aluta (QM G328460): C, external view of a single zooid; D, pallial wall showing gut and gonads on left side. Pyura scortea (QM G328138): E, external view. Molgula elva sp.nov. (WAM Z27525): F, detail of branchial infundibula; G, internal view showing body organs and muscualture. Scales: A, E, 0.5 cm; B–D, 0.2 cm; F, 0.5 mm; G, 1 mm.