Sigillina cyanea Herdman, 1899

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 : 1129-1130

Sigillina cyanea Herdman, 1899

Colella cyanea Herdman, 1899, p. 70 .

Sigillina cyanea: Kott 2007, p. 643 and synonymy.

Distribution

Previously recorded (see Kott 2007): Western Australia (Dampier Archipelago and south to King George’s Sound); New South Wales ( Port Jackson and north to Coffs Harbour); Queensland (Capricorn Group); Aru Is. New records: Western Australia CSIRO SS10 / 05 (Bald I., Stn 35, 200 m, 24.11.05, QM G328130 , Stn 38, 160 m, 24.11.05, QM G328131 ; Kalbarri, Stn 96, 435 m, 4.12.05, QM G328470 ) .

Description

The species is readily identified by its striking navy-blue colour, rope-like heads on a thick, relatively short cylindrical stalk (seldom longer than the head), separately opening zooids with characteristic short, wide thoraces with separate atrial and branchial siphons, three rows of stigmata, abdomen about the same length as the thorax with gonads in the gut loop, a long posterior abdominal vegetative stolon and a single embryo being incubated in a brood pouch at the postero-dorsal corner of the thorax.

Remarks

The Australian reports of this species seem to represent two populations, one that extends from the Dampier Archipelago to the southern coast of Western Australia at Bald Is. This population may extend into the Arafura Sea and Aru Is., although the species has not been recorded from other parts of Indonesia. It is not recorded from the southern coast east of Bald I. or from the south-eastern quarter of the continent south of Port Jackson and, although it has been recorded from the southern end of the Great Barrier Reef, its other records on the eastern coast are from a limited range on the central eastern coast between Port Jackson and Coffs Harbour. It is possible that the species favours hard substrates and strong currents (see Kott 2007) and there could be ecological/sampling reasons for its recorded range.

Sigillina grandissima Kott, 1990

( Figure 4A )

Sigillina grandissima Kott 1990a, p. 93 .

Distribution

Previously recorded (see Kott 1990a): Western Australia (northeast of Montbello Is., Dampier Archipelago ,? Northwest Cape , Houtman’s Abrolhos , Cervantes , Cockburn Sound , Great Australian Bight ). New record: Western Australia CSIRO SS10 / 05 (Zuydorp near Kalbarri, Stn 110, 106m, 06.12.05, QM G328124 ) .

Description

The newly recorded colony is a single tongue-shaped lobe 10 cm high, 4 cm wide and narrowing to the base where it is about 2 cm in diameter. Zooids open separately around the whole surface of the colony and project obliquely in toward the centre and base.

As previously described, the zooids are robust and branchial and atrial apertures are on short, six-lobed siphons, the branchial terminal and the atrial antero-dorsal. The thorax and abdomen are of about equal length. The stomach, about halfway down the abdomen, is almost spherical with a smooth wall.

In the newly recorded colony, a single large larva was found in a brood pouch in the test presumably separated from the postero-dorsal part of a thorax. Otherwise, neither larvae nor gonads were detected. The larvae are as previously described, although only two adhesive organs were detected with three large ampullae on each side. The central ampullae, level with the space between the two vertically placed adhesive organs, are longer than the dorsal and ventral pairs. The larval trunk is up to 4.0 mm long but the tail is relatively short, barely reaching the anterior end of the trunk. The terminal end of the tail has a wide vane around it.

Remarks

The new record is within the previously known geographic range of this robust species that appears to be well represented on the continental shelf of the western and southern coasts of the continent. Kott (1990a) noted a gap in its continuous range between Cockburn Sound and the Great Australian Bight. The new material is from the northern part of its known range at a greater depth than previously recorded. The larva is characteristic of this genus, with a large trunk, rounded lateral ampullae and two or three large adhesive organs with flat platforms of adhesive cells in the epidermal cups. This larva is similar to the larvae of other species in this genus, but with a trunk almost twice the length.

Figures

Figure 4. Sigillina grandissima (QM G328124): A, larva. Synoicum chrysanthemum (B2,3, C, QM G328097; B1, D, (QM G328060)): B1–3, colonies; C, thorax, abdomen and posterior abdomen (showing male follicles); D, larva. Scales: A, C, 0.5 mm; B, 2 cm; D, 0.2 mm.