Didemnum leopardus, 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 : 2447

Didemnum leopardus sp. nov.

( Figures 16B , 20E )

Distribution

Type locality: Northern Territory (Bynoe Harbour, Dawson Rock, 5–8 m, muddy bottom, coll. M. Browne, 10 June 2003, holotype QM G308719 ) .

Description

The colony is thin, hard and brittle and about 30 cm in extent. In preservative, it has a network of irregular cream depressions in the surface that separate it into a mosaic of white slightly elevated, zooid-free scale-like areas. In life, the depressions are brown and the scale-like areas are yellow. Spicules are crowded throughout the test. They are to 0.06 mm diameter with seven to nine robust conical rays in optical transverse section. Ventral surfaces of the thoraces are embedded in the solid test surmounted by these scale-like areas and two or three large sessile common cloacal apertures are on the highest points of the colony where the substrate probably raises it higher than the rest of the colony.

The zooids are contracted and the details of their structure were not determined. Gonads were not detected.

Remarks

The colonies of this species have a dramatic appearance. Its spicules resemble those of D. madeleinae and D. incanum but are larger with more rays and the colonies are different. Although the in situ photograph indicates that the living specimen resembles those of Didemnum poecilomorpha F. and C. Monniot, 1996 (see Kott 2001, Plate 13G), it is distinguished by the lack of plant cell symbionts and the presence of only one type of spicule (stellate ones with 11–13 rays in optical transverse section), the globular spicules present with the stellate ones in the latter species not being present.

Figures

Figure 16. Scanning electron micrographs of the calcareous spicules of: (A) Didemnum incanum (SAM E3238); (B) Didemnum leopardus sp. nov. (QM G308719, holotype); (C) Didemnum moseleyi (WAM 175.93); (D) Didemnum plebeium sp. nov. (WAM 155.93, syntypes); (E) Didemnum stragulum (WAM 162.93); (F) Didemnum ternerratum (SAM E3240); (G) Trididemnum amiculum (SAM E3263); (H) Trididemnum areolatum (QM G308746).

Figure 20. In situ images of: (A) Didemnum fragum (SAM E3266); (B) Didemnum fuscum (QM G308730); (C) Didemnum incanum (SAM E3252); (D) Didemnum jucundum (SAM E3236); (E) Didemnum leopardus (QM G308719, holotype); (F) Didemnum microthoracicum (SAM E3256); (G) Didemnum moseleyi (QM G308713); (H) Didemnum pellucidum (SAM E3271).