Lissoclinum clavatum, 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 : 2462

publication ID	https://doi.org/ 10.1080/00222930500087077
persistent identifier	https://treatment.plazi.org/id/7352D565-FB04-FF84-FE02-FF496467F925
treatment provided by	Felipe
scientific name	Lissoclinum clavatum
status	sp. nov.

Treatment

Lissoclinum clavatum View in CoL sp. nov.

( Figures 12B–D View Figure 12 , 17F View Figure 17 , 21F View Figure 21 )

Distribution

Type locality: South Australia (Kangaroo I., between Western River Cove and Snug Cove W of the Arch on rock wall, 10–12 m, coll. K. Gowlett Holmes, 15 November 2002, holotype SAM E3260 View Materials ; Pissy Boy Rock, on rock wall, 10 m, paratype SAM E3258 View Materials ) .

Description

The newly recorded colonies from South Australia are thin, hard, brittle plates or irregular encrusting colonies with spicules crowded throughout. Stellate branchial openings, their margins lined with spicules, are evenly distributed over the surface and are depressed into it in neat spicule-free circles of test. Circular common cloacal apertures with white, opaque rims are randomly placed on the surface. Spicules are small (to 0.035 mm diameter) and burr-like with 13–15 round-tipped, club-shaped rays in optical transverse section. In life, the colony is pale blue and white. In preservative, dark brown zooids (with brown cells in the haemocoel) can be seen through the common cloacal apertures and through the transparent spicule-free test around the branchial aperture. Clumps of zooids are in the test ligaments crossing the large common cloacal cavity from the surface to the basal test. These subdivide at the surface, separating thoraces from one another. Abdomina are partially or completely embedded in the basal test or are enclosed in the basal part of the test connective. These connecting pillars of test either are rigid with crowded spicules (SAM E3260), or the abdomina, seen through a single layer of spicules around the outside of the test connective, appear to be encased by a capsule of spicules.

Zooids have long, narrow thoraces with the large atrial opening exposing almost the whole of the branchial sac (with about six long narrow stigmata per half row) to the common cloacal cavity. Large oval lateral organs are on the body wall on each side of the endostyle. The abdomen is small and bent up underneath the thorax. Gonads were not detected in these specimens.

Remarks

The species is distinguished by its small spicules with relatively few, club-shaped rays. Superficially these colonies, with their blue pigment, depressed branchial apertures and dark haemocoelic cells look like specimens of the tropical species L. reginum Kott, 2001 which, however, has more extensive colonies and larger spicules with more and thinner rays. Lissoclinum levitum Kott, 2001 (see Kott 2004a) has different colonies with terminal common cloacal apertures protruding from the surface, and larger spicules with relatively few rays, although the latter are more pointed than the club-shaped rays found in the present species. Lissoclinum ostrearium ( Michaelsen, 1930) has a similar colony with the same extensive common cloacal cavity as the present species, however, the spicules shown by Kott (2001, Figure 176E) have more and thinner rays than the present species. Lissoclinum concavum has depressed branchial apertures and similar spicules (although it also has stellate spicules not observed in the present species), its colonies are soft without crowded spicules and a different colour and, even in the absence of the multiple testis follicles that would clearly indicate its identity, the species could not be mistaken for the present one.