Observations on non-didemnid ascidians from Australian waters (1)
Kott, Patricia
Journal of Natural History
2006
2006-04-26
40
3 - 4
169
234
53Y2F
Kott, 2006
Kott
2006
[444,748,725,749]
Ascidiacea
Polyclinidae
Synoicum
Animalia
Aplousobranchia
32
200
Chordata
species
sphinctorum
sp. nov.
( Figures 4D–F, 10C)
Distribution Type locality. South Australia( Kangaroo I. between Western River Cove and Snug Cove, ‘‘ The Arches’’, on rock wall, 10–14 m, coll. K. Gowlett Holmes, 14 November 2001, holotype SAM E3283).
Description The colony is a solid sandy mass, although the sand is crowded only on the surface and is sparse internally. The upper surface has dome-like elevations surrounded by about 10 branchial apertures and with a terminal common cloacal aperture. Broad sandy rounded ridges surround the domes. The branchial apertures are in the groove between the central dome and the marginal rounded ridge. The atrial aperture is on a brown-coloured siphon with a large, rounded muscular atrial lip projecting from the anterior rim of the opening. About three fine-pointed papillae are on the posterior rim of the atrial opening. Distinct sphincter muscles surround the atrial and branchial siphons. Gonads were not detected in the typecolony. A small papillum projects from the mid-dorsal line just behind the atrial opening. The zooids are obscured by the sand on the colony. The branchial sac has 18 rows of stigmata with about 20 ineach half row. The anus opens level with the seventh row of stigmata. The stomach is relatively small with 12 shallow, internal longitudinal folds, although these are not always seen in smaller zooids. Gonads were not detected, but the posterior abdomen is present with two narrow longitudinal muscles from the thorax extending along it.
Remarks Although the zooids and the systems are like those of S. concavitum Kott, 1992a, the sphincter muscles around the siphons are more conspicuous and the colony has more sand. Synoicum obscurum Kott, 1992ahas different colonies with two or three systems per lobe and only irregular creases (rather than longitudinal folds) in the stomach wall. The larva of the present species is not known.
2001-11-14
SAM
Kangaroo I. & K. Gowlett Holmes
12
The Arches'
32
200
E3283
1
South Australia
holotype