New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (part I)
Author
Kott, Patricia
text
Journal of Natural History
2004
2004-03-20
38
19
731
774
http://www.tandfonline.com/doi/abs/10.1080/00222930310001647334
journal article
10.1080/00222930310001647334
1464-5262
4653689
Leptoclinides exiguus
Kott, 2001
Leptoclinides exiguus
Kott, 2001: 62
and synonymy.
Distribution
. New records:
South Australia
(St Vincent Gulf, SAM E2906; Kangaroo I., SAM E2907). Previously recorded (see
Kott, 2001
):
South Australia
(Gulf St Vincent, Spencer Gulf, Kangaroo I.),
Victoria
(Phillip Bay, Western Port, Gabo I.).
Description
. Encrusting colonies of variable thickness (to
1 cm
) appear to accommodate irregularities in the substratum, while the surface remains relatively even. Irregular grey pigment particles are evenly scattered amongst the spicules in a layer at the level of the branchial siphons beneath a thin superficial spicule-free layer. These pigment particles become more sparse toward the base of the colony. Spicules are present throughout one of the colonies (SAM E2906) but are less crowded in the lower half. In the other specimen (SAM E2907) the basal half of the colony is completely aspiculate. Spicules are to
0.06 mm
diameter, stellate, with 11–13 rays in optical transverse section. Ray tips are chisel-shaped. Branchial apertures are along each side of the network of surface depressions over the oesophageal primary cloacal canals.
About 10 stigmata are in the first row of the branchial sac. The gut forms a simple vertical loop. Gonads are present only in one of the newly recorded specimens (SAM E2907). A circle of about six testis follicles has eight coils of the vas deferens around it.
Remarks
. The newly recorded colonies have characteristic zooids (with rather square thoraces and vertical gut loops) arranged along each side of circular oesophageal common cloacal canals as described for this species. Revision of the type material shows the spicules to have 11–13 rays (rather than the 9–11 Kott recorded), and eight coils of the vas deferens have been detected in the
holotype
(QM G301615) rather than the six Kott reported. One of the newly recorded specimens (SAM E2906) differs from others assigned to this species in having more crowded spicules in the basal half of the colony. They are, however, less crowded in the base than in the upper half of the colony, a difference that would not preclude conspecificity.