Didemnum tumulatum Kott, 2004

Kott, Patricia, 2007, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (part 4), Journal of Natural History 41 (17 - 20), pp. 1163-1211 : 1192

Didemnum tumulatum Kott, 2004

( Figure 10E )

Didemnum tumulatum Kott 2004c, p 58 .

Distribution

Previously recorded (see Kott 2004c): Ashmore Reef. New record: Queensland (Great Barrier Reef: 18.325 ° S, 146.595 ° E, 41 m, QM G308873 ) .

Description

The colony is a thin sheet encrusting a Murex shell. Black pigment is in the upper half of the colony including the surface test over the common cloacal canals and around the common cloacal apertures, which are on the higher parts of the colony. Zooids line each side of the common cloacal canals, which surround irregular zooid-free areas that appear from the surface as blotches. Spicules (to 0.06 mm diameter) are stellate, with 9–11 long conical rays in optical transverse section. Zooids are small with a long retractor muscle projecting from halfway down the oesophageal neck. Seven coils of the vas deferens surround the undivided testis.

Remarks

Spicules are like those of Didemnum caesium Sluiter, 1909 and D. stragulum Kott, 2001 but are smaller. The spicules of D. granulatum Tokioka, 1954 are similar, although its common cloacal cavity is a large horizontal space unlike the circular canals in the present species. Didemnum υia Kott, 2001 has similar colonies but slightly larger spicules and 11 coils of the vas deferens.

Figures

Figure 10. Scanning electron micrographs. (A–C) Didemnum psammatode [(A, B) QM G308820; (C) QM G308831]; (D) Didemnum tantalum (QM G308860); (E) Didemnum tumulatum (QM G308873); (F) Didemnum υesica (QM G308875); (G) Didemnum υiride (QM G308864); (H) Trididemnum farrago (QM G308819).