Didemnum cilicium, Kott, 2005

Kott, Patricia, 2005, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (Part 3), Journal of Natural History 39 (26), pp. 2409-2479 : 2438

Didemnum cilicium sp. nov.

( Figures 6A,B, 15E , 19F )

Distribution

Type locality: South Australia (Kangaroo I. between Western River Cove and Snug Cove, Pissy Boy Rock W side, 6–8 m on rock wall, coll. K. Gowlett Holmes, 22 November 2002, holotype SAM E3251 ) .

Description

The surface of the colony is divided into opaque scale-like elevations separated from one another by narrow circular depressions. In preservative, the test over these depressed areas is relatively thin and is slightly translucent and beige colour, while the elevated areas they enclose, which surmount solid pillars of test, are white with crowded spicules. The spicules are stellate, to 0.07 mm diameter, with 9–11 conical, sometimes blunt-tipped rays in optical transverse section. The circular common cloacal canals vary in depth, sometimes extending the depth of the thoraces, but sometimes the whole depth of the zooids.

Thoraces are small, with a fine retractor muscle from halfway down the oesophageal neck. Large sessile atrial apertures lack an atrial tongue. The branchial lobes are triangular and pointed and the siphon is contracted but conspicuous and may be long in more relaxed zooids. Large yellow eggs are in the abdomen (which is embedded in the basal test) but testes were not detected.

Remarks

The zooid-free scale-like elevations on the upper surface, like those in D. grande Herdman, 1886 and D. microthoracicum Kott, 2001 , are larger and a different colour from those of D. poecilomorpha F. and C. Monniot, 1996 and D. leopardus sp. nov. The species is distinguished from others by its relatively large spicules with 9–11 robust conical rays crowded throughout the colony and by the form of the common cloacal systems and the quilted colony surface.

Figures

Figure 15. Scanning electron micrographs of the calcareous spicules of: (A) Polysyncraton millepore (WAM 122.93); (B) Polysyncraton orbiculum (WAM 128.90); (C) Polysyncraton papyrus (SAM E3253); (D) Didemnum astrum (WAM 601.89); (E) Didemnum cilicium sp. nov. (SAM E3251, holotype); (F) Didemnum corium sp. nov. (SAM E3249, holotype); (G) Didemnum cygnuus (QM G308716); (H) Didemnum fragum (SAM E3266).

Figure 19. In situ images of: (A) Polysyncraton glaucum (QM G308736); (B) Polysyncraton papyrus (SAM E3253); (C) Polysyncraton pedunculatum (SAM E3272); (D) Polysyncraton purou (QM G308707); (E) Polysyncraton rica (SAM E3245); (F) Didemnum cilicium (SAM E3251, holotype); (G) Didemnum corium (SAM E3249, holotype); (H) Didemnum cygnuus (QM G308716).