Trididemnum areolatum ( Herdman, 1906 )

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 : 2455

Trididemnum areolatum ( Herdman, 1906)

( Figure 16H )

Didemnum areolatum Herdman 1906, p 337 .

Trididemnum areolatum: Kott 2001, p 258 and synonymy.

Distribution

Previously recorded (see Kott 2001): Queensland (Hervey Bay–Lizard I.); Central Pacific (Kure and Line Is); French Polynesia; New Caledonia; Indian Ocean ( Sri Lanka). New record: Northern Territory (Bynoe Harbour, QM G308746).

Description

The newly recorded specimen is a gelatinous, encrusting colony of even thickness. A superficial layer of bladder cells mixed with some black pigment particles and some sparse spicules overlies a single layer of spicules. Spicules also are in a layer lining the common cloacal cavities. The spicules are large (to 0.1 mm diameter) and have 13–15 stubby short conical to rounded rays in optical transverse section.

Zooids have black squamous epithelium and a black endostylar pigment cap. In this specimen the gut is filled with large, muddy faecal pellets that obscure the zooids. Eight coils of the vas deferens surround the undivided testis.

Remarks

Differences from previously recorded specimens were not detected.

Figures

Figure 16. Scanning electron micrographs of the calcareous spicules of: (A) Didemnum incanum (SAM E3238); (B) Didemnum leopardus sp. nov. (QM G308719, holotype); (C) Didemnum moseleyi (WAM 175.93); (D) Didemnum plebeium sp. nov. (WAM 155.93, syntypes); (E) Didemnum stragulum (WAM 162.93); (F) Didemnum ternerratum (SAM E3240); (G) Trididemnum amiculum (SAM E3263); (H) Trididemnum areolatum (QM G308746).