Synoicum implicatum, Kott, 2008

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 : 1136-1138

Synoicum implicatum sp. nov.

( Figures 5A–C )

Distribution

Type locality: Western Australia CSIRO SS10 / 05 (Pt. Hillier, Stn 57, 117.1970E 35.3735S, 195– 6 m, 27 November 2005, holotype WAM Z27523 , QM G328098 ) .

Description

The holotype is a massive, sandy hemisphere with generally club-shaped lobes around the outer surface, each containing a separate cloacal system with zooids surrounding a central terminal common cloacal aperture. These lobes are partially fused to one another along their length by the sand that adheres to their surface. Sand is also crowded throughout the test. The zooids extend down the length of each lobe, almost to the base. Clumps of minute spherical orange bodies are in the test associated with each zooid, which also is orange.

The branchial aperture has six moderately long lobes around it. A long muscular atrial tongue divided into about three long lobes arises from the anterior rim of the short siphon. About 20 rows of crowded stigmata are in the branchial sac. The smooth stomach is long, almost cylindrical. A conspicuous globular posterior stomach is in the gut loop. The zooids are in replicative mode and the long posterior abdomina are filled with trophozoite cells.

Remarks

The gut loop, branchial and atrial apertures are like those of S. buccinum but the zooids are longer, with more rows of stigmata and the cloacal systems with numerous systems in each lobe are different. However, colonies like the present one (consisting of separate lobes crowded together, adhering to one another along their length and joined basally) do occur in other species in this genus. Such colonies occur in S. intercedens ( Sluiter, 1909) , which is distinguished by its pouched stomach wall and Synoicum obscurum Kott, 1992 from the south-eastern corner of the continent. Although the irregular markings on the stomach wall of the latter species that Kott (1992a) thought were unique probably are artefacts, it is distinguished from the present species by its smaller atrial opening and the absence of the long atrial tongue of the present species.

Figures

Figure 5. Synoicum implicatum sp. nov. (QM G328098): A, colony; B, thorax and abdomen; C, antero-dorsal part of thorax. Synoicum laboutei (QM G328443): D colony; E, thorax and abdomen, both very much contracted. Synoicum macroglossum (QM G328104): F, thorax; G, abdomen and posterior abdomen. Synoicum obscurum (QM G328461): H, larva. Scales: A, D, 2.0 cm; B, 1.0 mm; C, E–G, 0.5 mm; H, 0.1 mm.