Leptoclinides pulvinus, 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 : 2424-2425

Leptoclinides pulvinus sp. nov.

( Figures 3A–D , 14F )

Distribution

Type locality: Northern Territory (Bynoe Harbour Moira Reef rocky reef on rock, 5–8 m, coll. B. Glasby and party, 25 June 2003, holotype QM G308742 ) .

Description

In preservative, the colony is a robust, brown slab. The surface has a regular quilt-like pattern of bolster-like elevations, which comprise about one-quarter of the total thickness of the colony and are separated from each other by deep narrow depressions. Occasional large, soft, funnel-like common cloacal apertures about 1–2 cm apart are on the surface between the surface elevations. A thick spicule-free superficial bladder cell layer containing brown pigment cells covers the surface elevations. Similar brown pigment cells surround the zooids, lying free in the space between the test and the body wall of the zooids. Spicules are in a layer beneath the superficial bladder cell layer, but are completely absent from the translucent basal half of the colony. A thin layer of test forming the roof of the deep common cloacal canals is at the base of each of the surface depressions and the branchial openings of the zooids are along each side of the base of these depressions. The common cloacal canals are deep, extending at least the full length of the zooids (about three-quarters of the depth of the colony). Spicules are of moderate size with five to seven long, narrow pointed arms in optical transverse section. The ray length/spicule diameter ratio is about 0.5.

Zooids are robust but contracted and this together with the scattered brown pigment cells that surround them and the spicules in the surrounding test obscure them and the number of stigmata in the branchial sac. The posterior atrial siphons, each with five minute pointed lobes around the aperture, open into each side of the top of the common cloacal canals. Abdomina are large with a relatively voluminous gut sometimes forming a vertical loop and sometimes with the post-pyloric part bent at right angles to the longitudinal axis of the zooid. Five coils of the vas deferens surround about five or six large testis follicles.

Remarks

Both the colonies (with the regular quilted pattern, the deep depressions over the common cloacal canals that interrupt the spicule layer, the thick superficial layer of bladder cells) and the spicules with their long, narrow arms are unusual in this genus. Both colonies and spicules differ from those of L. constellatus Kott, 2001 , L. exiguus Kott, 2001 , and L. rigidus Kott, 2001 , the colonies of the present species having a larger and more regular quilted pattern and a thicker superficial layer of bladder cells, and the spicules having fewer, longer and thinner and invariably pointed rays (rather than sometimes having the chisel-shaped rays of the other species).

The brown pigment cells that are scattered around the outside of the zooids in this species resemble those found in some Didemnum spp. (e.g. D. sordidum Kott, 2001 ).

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 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).