Didemnum fuscum Sluiter, 1909

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 : 2443

Didemnum fuscum Sluiter, 1909

( Figure 20B )

Didemnum fuscum Sluiter 1909, p 52 ; Kott 2001 p 184 and synonymy; 2004c, p 40.

Distribution

Previously recorded (see Kott 2001): Western Australia (Port Hedland); Queensland (S. Great Barrier Reef); Northern Territory (Timor Sea); Indonesia. New record: Northern Territory (Bynoe Harbour, QM G308729-30).

Description

One of the newly recorded colonies (QM G308730) is rather irregular, with the surface raised into rounded lobes with two or three large sessile common cloacal apertures with white crowded spicules in the rim of each opening. The living specimens are whitish beige. In preservative, black spherical bodies lie free in the spaces around the zooids (rather than being embedded in the test) and the brown-black colour of the zooids dominates the colonies. Thoraces are small with a long retractor muscle from halfway down the oesophageal neck. The spicules have the characteristic club-shaped spicule rays crowded through the colony as previously described for this species. Brown larvae are present in specimens collected in July.

Remarks

Although all characters are as previously described, including the larvae, the newly recorded colony is whitish beige rather than the range of colours that Kott (2001) reported for the living specimens.

Figures

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).