Didemnum fragile 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 : 2441

Didemnum fragile Sluiter, 1909

Didemnum fragile Sluiter 1909, p 56 (part ZMA TU446.1 part B) and synonymy; Kott 2001, p 177; 2004c, p 40.

Distribution

Previously recorded (see Kott 2001): Western Australia (The Kimberley); Northern Territory (Timor Sea); Queensland (Great Barrier Reef); Indonesia; Palau Is; Fiji. New record: Northern Territory (Bynoe Harbour, QM G308741).

Description

The newly recorded colony is a thin, encrusting sheet with burr-like spicules to 0.05 mm diameter crowded throughout. In life, the specimen is a greenish grey with a mosaic of small yellow flecks in the surface. In preservative, the colony is grey with a white margin around the colony. Although they occupy the whole depth of the colony, the zooids are small with no more than six stigmata per row, a rounded atrial lip and dark cells in the haemocoel. The grey colour of the colony results from the dark zooids seen through the white spicules in the surface layer of test.

Remarks

The species is similar to D. albopunctatum Sluiter, 1909 and D. parancium Kott, 2001 , both of which have crowded burr-shaped spicules in thin colonies. However, in the present species the spicules are larger. Further, the zooids of D. parancium are larger than the present species and they have characteristic large transparent vesicles in the haemocoel that have not been detected in D. fragile .