Didemnum, Savigny, 1816

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 : 1193-1194

Didemnum IJiride ( Herdman, 1906)

( Figure 10G )

Leptoclinum υiride Herdman 1906, p 340.

Didemnum υiride: Kott 2001, p 248 and synonymy.

Distribution

Previously recorded (see Kott 2001): Western Australia (Montebello Is); Queensland (Heron I., Swain Reefs); Western Pacific ( Papua New Guinea; French Polynesia); Indian Ocean ( Sri Lanka). New record: Queensland (Great Barrier Reef: 18.275 ° S, 146.455 ° E, 29 m, QM G308864 ) .

Description

Stellate spicules (to 0.055 mm diameter) are crowded throughout the test. They have five to seven conical rays in optical transverse section. Oval patches of green algal cells (Cyanophyta) are in the basal test. Conspicuous terminal ampullae of stolonic vessels are also in the basal test. The branchial siphon is moderately long, the thorax is small, and a retractor muscle projects from halfway down the short oesophageal neck. The testis is undivided and is surrounded by seven coils of the vas deferens.

Remarks

The patches of algal cells in the basal test and the size and form of the stellate spicules contribute to the identification of this species.

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).