Leptoclinides rigidus 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 : 2425-2426

Leptoclinides rigidus Kott, 2001

( Figures 3E , 18E )

Leptoclinides rigidus Kott 2001, p 77 and synonymy; 2004b, p 2474.

Distribution

Previously recorded (see Kott 2001, 2004b): Western Australia (Montebello Is, Ashmore Reef); Queensland (Whitsunday Is, Deloraine I., Hawkesbury I.); Northern Territory (Wessel I., Darwin); Papua New Guinea. New records: Western Australia (Dirk Hartog I., Shark Bay, WAM 1070.89); Northern Territory (Darwin, QM G308708 G308718).

Description

The newly recorded colonies are tough irregular sheets with a smooth surface. A thin superficial bladder cell layer is interrupted by the branchial siphons and their plugs of spicules in the siphon linings. The test is translucent, the spicules being only moderately crowded in the upper part of the colony. They also line the common cloacal cavities but are sparse in the base and up to the basal one-third of the total thickness of the colony. The primary common cloacal canals are deep and some extend into posterior abdominal cavities. Owing to the not very crowded spicules, preserved colonies appear to have a grey network where the deep primary canal interrupts the thickness of the spicules through the depth of colony. This results in the thin layer of surface test over the common cloacal canals being translucent and grey. However, in situ photographs show the living colonies to be blue, sometimes with some brown flecks. Spicules are characteristically stellate, to 0.08 mm diameter with 9–11 pointed to chisel-tipped conical rays in optical transverse section.

Zooids have a simple vertical gut loop, five coils of the vas deferens and four to eight testis follicles.

Larvae, with a trunk 0.75 mm long, are recorded for the first time in colonies collected from Darwin (QM G308708). They have three lateral ectodermal ampullae on each side of the three antero-median adhesive organs and a lateral horizontal ampulla on the left side of the trunk.

Remarks

The tough colonies, stellate spicules, common cloacal canals and the absence of spicules from the basal part of the colony are characteristic of this species. The blue colour of the living colonies also may be characteristic and distinguishes the species from L. constellatus Kott, 2001 and L. pulvinus sp. nov., which also have a quilted surface but are brown and beige. The temperate species L. seminudus Kott, 2001 also has a quilted surface and similar spicules, but lacks a posterior abdominal cloacal cavity and has a larval trunk only 0.4 mm long (see below). Leptoclinides exiguus Kott, 2001 has spicules with more numerous rays.

Figures

Figure 3. (A–D) Leptoclinides pulvinus sp. nov. (QM G308742, holotype): (A) colony surface; (B) vertical section through colony (semi-diagrammatic); (C) thorax; (D) abdomen. (E) Leptoclinides rigidus (QM G308708): larva. Scale bars: 1.0 cm (A); 1.0 mm (B); 0.1 mm (C–E).

Figure 18. In situ images of: (A) Leptoclinides decoratus (SAM E3257); (B) Leptoclinides frustus (SAM E3255, holotype); (C) Leptoclinides imperfectus (SAM E3243); (D) Leptoclinides lissus QM G308709); (E) Leptoclinides rigidus (QM G308708); (F) Leptoclinides seminudus (SAM E3264); (G) Polysyncraton cuculliferum (QM G308715); (H) Polysyncraton galaxum (SAM E3261).