Didemnum jedanense Sluiter, 1909

Kott, Patricia, 2008, Ascidiacea (Tunicata) from deep waters of the continental shelf of Western Australia, Journal of Natural History 42 (15 - 16), pp. 1103-1217 : 1182-1183

Didemnum jedanense Sluiter, 1909

( Figure 17G ) Didemnum jedanense Sluiter 1909, p. 59 . Kott 2001, p. 194; 2007, p. 1182 and synonymy.

Distribution

Previously recorded (see Kott 2007). Western Australia (Cape Ruthiers); Queensland (Hervey Bay, Abbot Point, Mossman, Great Barrier Reef; Northern Territory (Darwin), Indonesia New record: Western Australia CSIRO SS10/05 (Bald I., Stn 35, 157 m, 24.11.05, QM G328005).

Previously known only from tropical waters, the new record from the southern coast of Western Australia is the most southerly location recorded for the species. The species appears to be a common component of continental shelf ascidian communities of the Indo-West Pacific.

Description

Scraps of white didemnid colony are found encrusting sponge and rubble. The test is translucent, and although it has some sand embedded this may be an artefact of the collecting method which has badly damaged the colony.

Calcareous spicules are in a layer beneath the spicule-free superficial surface of the colony, and some project down into the lining of the branchial siphons. Spicules have 17–19 long, crowded, more or less fusiform, irregular to pointed-tipped rays in optical transverse section, and are to 0.055 mm diameter.

Zooids are robust, with a vertical gut loop. Eight coils of the vas deferens spiral around the outer half of the almost spherical and undivided testis.

Remarks

The robust zooids, fleshy colonies and the almost burr-like spicules of this species, with their long crowded rays, are distinctive. However the arrangement of spicules in the colony is variable. The scraps of the newly recorded specimens are too mutilated to determine the arrangement of zooids in the colonies.

Figures

Figure 17. Scanning electron micrographs of didemnid spicules: A, Polysyncraton millepore, QM G328050; B, Polysyncraton?palliolum, QM G328161; C, Polysyncraton pavimentum, QM G328058; D, Didemnum?candidum, QM G328457; E, Didemnum cygnuus, QM 328456; F, Didemnum dolium, QM G328008; G, Didemnum jedanense, QM G328005; H, Didemnum moseleyi, QM G328455.