Trididemnum farrago Kott, 2004

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 : 1194

Trididemnum farrago Kott, 2004

( Figure 10H )

Trididemnum farrago Kott 2004c, p 61 and synonymy.

Distribution

Previously recorded (see Kott 2004c): Torres Strait. New records: Queensland (Great Barrier Reef: 18.615 ° S, 146.465 ° E, 23 m, QM G308819 ) .

Description

Colony is a smooth, irregular, thin sheet. Dark pigment is in the thick spicule-free superficial bladder cell layer, beneath which is a layer of crowded spicules (at thorax level). Another layer of spicules is beneath the thoracic common cloacal canals. Spicules are stellate, to 0.1 mm diameter with 11–15 stumpy to long conical rays in optical transverse section, although many of the rays are broken off.

The zooids have six pointed branchial lobes, a short retractor muscle from halfway down the oesophageal neck, and a posteriorly orientated atrial siphon.

Remarks

Spicules are relatively large although smaller than those of T. amiculum , and sometimes they have more stumpy rays and rays of varying lengths. The spicules, with their relatively short stumpy rays, are also similar to those of T. planum (see Kott 2001, 2002, 2004c) although the spicule rays of the latter species are less variable and the spicules themselves are smaller than those of T. farrago .

Figures

Figure 10. Scanning electron micrographs. (A–C) Didemnum psammatode [(A, B) QM G308820; (C) QM G308831]; (D) Didemnum tantalum (QM G308860); (E) Didemnum tumulatum (QM G308873); (F) Didemnum υesica (QM G308875); (G) Didemnum υiride (QM G308864); (H) Trididemnum farrago (QM G308819).