New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (part 4)
Author
Kott, Patricia
text
Journal of Natural History
2007
2010-07-29
41
17 - 20
1163
1211
http://dx.doi.org/10.1080/00222930701359218
journal article
10.1080/00222930701359218
1464-5262
4669578
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
.