Trididemnum nobile 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 : 2456-2457

Trididemnum nobile Kott, 2001

( Figures 11A,B , 17B , 21B )

Trididemnum nobile Kott 2001, p 272 and synonymy; 2004a, p 763 and synonymy.

Distribution

Previously recorded (see Kott 2001, 2004a): Western Australia ( Port Hedland , Cervantes) ; South Australia (Great Australian Bight, Sir Joseph Banks Is, Reevesby I., West I., Pearson I., Port Bonython , Gulf St Vincent, Investigator Strait, Williunga Reef, Kangaroo I.); Victoria (Phillip I., Portsea, Lorne); Queensland (Caloundra). New record : Tasmania ( Port Davey , SAM E3262 ) .

Description

As previously described, these complex, spongy colonies are large three-dimensional reticula formed by parts of the colony overgrowing the surface and subsequently fusing with it to enclose secondary spaces within the colony. Sometimes weed and other foreign material is incorporated in the test. The common cloacal cavities are three-dimensional with extensive posterior abdominal cavities. Common cloacal apertures are along ridges on the surface and have yellow pigment surrounding them. The spicules are to 1.35 mm diameter, which is larger than previously reported for this species, but they are otherwise identical, having seven to nine sharply pointed conical rays in optical transverse section. They are distributed throughout the colony.

Zooids are small, covered with black squamous epithelium. They have a short retractor muscle from the posterior end of the thorax. Ten tight coils of the vas deferens surround the undivided testis.

Remarks

Spicule distribution in this species is known to be variable, sometimes being present throughout as in the present colony, sometimes being present on the upper surface and in other specimens being sparse or absent altogether (see Kott 2004a). The colony is usually grey in preservative, owing to the black squamous epithelium on the zooids seen through the white spicules and translucent test. This species is distinguished from others by its 10 tight vas deferens coils.

Figures

Figure 11. Trididemnum nobile (SAM E3262). (A) Thorax; (B) abdomen. Scale bars: 0.1 mm.

Figure 17. Scanning electron micrographs of the calcareous spicules of: (A) Trididemnum dispersum (WAM 1044.89); (B) Trididemnum nobile (SAM E3262); (C) Trididemnum pigmentatum (QM G308714); (D) Lissoclinum agriculum sp. nov. (WAM 179.93, syntypes); (E) Lissoclinum bistratum (WAM 1018.89); (F) Lissoclinum clavatum sp. nov. (SAM E3260, holotype); (G) Lissoclinum coactum (WAM 120.90); (H) Lissoclinum diversum (WAM 153.86).

Figure 21. In situ images of: (A) Trididemnum amiculum (SAM E3263); (B) Trididemnum nobile (SAM E3262); (C) Trididemnum pigmentatum (QM G308714); (D) Trididemnum savignii (QM G308721); (E) Lissoclinum calycis (QM G308749); (F) Lissoclinum clavatum (SAM E3260, holotype); (G) Lissoclinum concavum (SAM E3242); (H) Lissoclinum levitum (SAM E3254).