Didemnum jedanense Sluiter, 1909

Kott, Patricia, 2007, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (part 4), Journal of Natural History 41 (17 - 20), pp. 1163-1211 : 1182

Didemnum jedanense Sluiter, 1909

( Figures 2E , 8F )

Didemnum jedanense Sluiter 1909, p 59 ; Kott 2001, p 194 and synonymy; 2004c, p 55.

Distribution

Previously recorded (see Kott 2004c): Western Australia (Cape Ruthiers); Queensland ( Hervey Bay , S. Great Barrier Reef, Abbott Point, Lizard I., Low Isles, Mossman); Northern Territory (Darwin); Western Pacific ( Indonesia, New Caledonia). New records: Queensland (Great Barrier Reef: 14.715 ° S, 145.405 ° E, 26 m, QM G308846 , G308862 , G308872 ; 16.155 ° S, 145.865 ° E, 57 m, QM G308848 ; 16.955 ° S, 146.425 ° E, 55 m) .

Description

Large encrusting gelatinous sheet growing over bryozoan skeletons have black pigment in the surface test and in upper half of colony or throughout. Zooids are in clumps in branching test connectives that cross the extensive common cloacal cavity. Thoraces are separate, enclosed in an independent sheet of test at the surface. The surface test is quilted, being depressed over the deep, uninterrupted common cloacal cavity that surrounds each clump of zooids and is lined on each side with zooids. A layer of bladder cells is in the surface test, overlying the spicules which are not present over the deep primary common cloacal cavities. Spicules are burr-shaped, to 0.04 mm diameter with rod-shaped rays, occasionally with pointed tips. Zooids have large (but contracted) thoraces, long fine retractor muscles of varying lengths, short oesophageal necks and double gut loops. The testis is entire and surrounded by eight coils of the vas deferens. Larvae are sturdy with a large trunk to 0.75 mm long with up to two blastozooids and six ectodermal ampullae along each side of the three antero-median adhesive organs.

Remarks

Despite a superficial resemblance to Polysyncraton meandratum (also with a quilted surface), the roomy common cloacal cavities, the rod-like spicule rays (compared with the conical pointed ones in the latter species), the small burr-like spicules, the dark pigment, and the eight coils of the vas deferens are all characteristic of D. jedanense , as are the larvae with blastozooids and six pairs of ectodermal ampullae.

Figures

Figure 2. (A, B) Didemnum abradatum (QM G308870, holotype): (A) zooid; (B) larva. (C, D) Didemnum fragum (QM G308826): (C) colony; (D) larva. (E) Didemnum jedanense (QM G308862): larva. Scale bars: 0.1 mm (A, B, D, E); 1 cm (C).

Figure 8. Scanning electron micrographs. (A) Didemnum coralliforme (QM G308861); (B) Didemnum crescente (QM G308815); (C) Didemnum fragum (QM G308826); (D) Didemnum grande (QM G308867); (E) Didemnum granulatum (QM G308843); (F) Didemnum jedanense (QM G308846); (G) Didemnum lissoclinum (QM G308814); (H) Didemnum mantile (QM G308887).