Polyclinum incrustatum Michaelsen, 1930

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 194

Polyclinum incrustatum Michaelsen, 1930

( Figures 3D , 9D )

Polyclinum neptunium f. incrustatum Michaelsen 1930, p 542 .

Polyclinum incrustatum: Kott 1992a, p 450 and synonymy.

Distribution

Previously recorded (see Kott 1992a): Western Australia (Bunbury, Albany ); South Australia ( Great Australian Bight , Spencer Gulf ); Victoria ( Portland ). New record: Tasmania ( Port Davey , 4–6 m, SAM E3274 ) .

Description

The colonies are as previously described, soft, grey oval pillows, with sand in the surface, although it is only sparse internally. Common cloacal apertures, slightly orange in the newly recorded specimens, are evenly distributed and protrude slightly from the otherwise smooth surface of the colony. Each cloacal aperture contains the very long, narrow atrial lips of the circle of zooids that surround it. These atrial lips project from the body wall just anterior to the small, round atrial opening of each zooid and they appear to close down over the forward-projecting atrial opening. A small post-atrial papillum also projects from the middorsal line. Zooids have 18 rows of about 14 stigmata per half row, and about the same number of flat, rounded branchial papillae on each of the transverse interstigmatal vessels. Gonads were not detected in the newly recorded colonies, and a long, narrow posterior abdominal vegetative stolon is present.

Remarks

The specimens are consistent with those described previously for this species. It is distinguished from Poyclinum marsupiale by its more numerous rows of stigmata, the less protuberant common cloacal apertures and the crowded zooids in complex systems rather than the circular systems of zooids that surround each common cloacal aperture in P. marsupiale , and when embryos are present, by the lack of a brood pouch projecting from the thorax.

Figures

Figure 3. (A–C) Pseudodistoma pilatum (SAM E3244): (A) thorax and oesophageal neck; (B) posterior end of abdomen; (C) end of posterior abdomen. (D) Polyclinum incrustatum (SAM E3274): thorax and abdomen. Scale bars: 0.2 mm.

Figure 9. In situ images of: (A) Pseudodistoma gracile (SAM E3270); (B) Pseudodistoma inflatum (SAM E3297); (C) Pseudodistoma pilatum (SAM E3296); (D) Polyclinum incrustatum (SAM E3274); (E) Polyclinum marsupiale (SAM E2866); (F) Aplidiopsis confluata (SAM E3281); (G) Aplidiopsis confluata (SAM E3282); (H) Synoicum citrum (SAM E3277).