Leptoclinides frustus, Kott, 2005

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 : 2419-2420

Leptoclinides frustus sp. nov.

( Figures 1A,B , 14C , 18B )

Distribution

Type locality: South Australia (Kangaroo I. between Western River Cove and Snug Cove, west of the Arch, Fred’s , on rock wall, 10–12 m, coll. K. Gowlett Holmes, 15 November 2002, holotype SAM E3255 ) .

Description

The colony is a small, thin irregular cushion, in life a pale yellow colour with opaque rims of crowded spicules around the large sessile common cloacal apertures randomly distributed over the surface. Branchial apertures, containing a plug of white spicules, are slightly depressed into the surface. Spicules are mixed with bladder cells in the superficial layer of test and are present, but not crowded through the remainder of the colony, being absent only from the base. Spicules are stellate, to 0.06 mm diameter, with 9–11 rays with chiselshaped or conical pointed tips and a ray length/diameter ratio of 0.24. The common cloacal cavity is a horizontal space at oesophageal level.

Zooids have a moderately long, funnel-shaped branchial siphon. Atrial siphons are short, opening directly into the oesophageal common cloacal cavity. The oesophageal neck is relatively long and the abdomen is bent up at right angles to the longitudinal axis of the thorax. Stigmata are obscured by contraction and the number was not determined. Gonads are not present.

Remarks

Owing to contraction and the absence of gonads in this specimen, its identification is based on the shape and size of the spicules, the form of the colony and the configuration of the common cloacal systems. Leptoclinides placidus Kott, 2001 from central Queensland has similar spicules throughout the colony, including their presence in the superficial bladder cell layer, but a more extensive three-dimensional common cloacal cavity with posterior abdominal spaces.

Figures

Figure 1. (A, B) Leptoclinides frustus sp. nov. (SAM E3255, holotype): (A) vertical section through a common cloacal canal (semi-diagrammatic); (B) zooid. (C) Leptoclinides lissus (QM G308709): larva. Scale bars: 0.5 mm (A); 0.1 mm (B, C).

Figure 14. Scanning electron micrographs of the calcareous spicules of: (A) Leptoclinides decoratus (SAM E3257); (B) Leptoclinides dubius (WAM 1093.89); (C) Leptoclinides frustus sp. nov. (SAM E3255, holotype); (D) Leptoclinides kingi (WAM Z20557); (E) Leptoclinides minimus sp. nov. (WAM 30.84, holotype); (F) Leptoclinides pulvinus sp. nov. (QM G308742, holotype); (G) Polysyncraton galaxum (SAM E3250); (H) Polysyncraton glaucum (QM G308736).

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).