Didemnum mantile Kott, 2001

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 : 2447-2448

Didemnum mantile Kott, 2001

Didemnum mantile Kott 2001, p 203 .

Distribution

Previously recorded (see Kott 2001): South Australia (Franklin I.); Victoria, Western Port). New record: southern Western Australia (E. end of Mason Bay , WAM119.90 ) .

Description

The newly recorded colony is white, encrusting, with a white lumpy surface. Evenly distributed stellate branchial apertures have spicules lining their margins. Spicules, crowded throughout, are to 0.04 mm diameter and have seven to nine relatively long conical but blunt-tipped rays in optical transverse section. The colony is contracted and details of the zooid morphology are obscure.

Remarks

This temperate species is known only from two previous records from south-eastern Australia and the new record extends its known range across the southern coast to the western end of the Great Australian Bight. Kott (2001) found only five to seven rays in optical transverse section, but a revision of the micrographs has shown the rays to be identical with those of the present specimen, i.e. seven to nine in optical transverse section. The small spicules with long rays resemble those of the tropical D. domesticum Kott, 2004c , which has a more robust colony with a smooth surface. The type specimens of the present species have a quilted surface resulting from depressions over the common cloacal canals that surround groups of zooids. This quilting is not evident in the newly recorded specimen. However, larvae of D. mantile , though at present not known, may be found to distinguish these species from one another. Didemnum microthoracicum also has spicules with seven to nine rays but they are larger than in the present species, being to 0.09 mm diameter.