Leptoclinides vesica, Kott, 2008

Kott, Patricia, 2008, Ascidiacea (Tunicata) from deep waters of the continental shelf of Western Australia, Journal of Natural History 42 (15 - 16), pp. 1103-1217 : 1170-1171

Leptoclinides vesica sp. nov.

( Figure 16D )

Distribution

Type locality: Western Australia CSIRO SS10 / 50 (Zuytdorp, Stn 104, 113.101E 27.0517S, 97 m, 05.12.05, holotype WAM Z27531 , QM G328458 ) .

Description

The holotype is a hard, encrusting slab with spicules crowded throughout. Terminal common cloacal apertures are on a number of rounded prominences on the surface of the colony and large common cloacal cavities are beneath these apertures. Colourless vesicles interrupt the spicules in the surface of the colony between the branchial apertures of the zooids. Spicules are large (to 0.084 mm diameter) and stellate with 13–15 rays in optical transverse section. The rays are conical but rather blunt-tipped.

Zooids are small and contracted with relatively short branchial siphons with six shallow but pointed lobes around the margin of the aperture. The atrial siphon projects back from the posterior third of the dorsal surface. The branchial sac has four rows of about 10 stigmata in each half row. Eight coils of the vas deferens surround four or five testis follicles. A retractor muscle was not detected. Four short vascular stolons project from the ventral concavity of the gut loop.

Remarks

Although the form of the encrusting colony of this species (with surface swellings and their terminal common cloacal apertures) is not unusual in this genus, the species has a number of characteristics that distinguish it from other species of Leptoclinides .

The characteristic colourless vesicles resemble those arranged in circles in the surface test around the branchial apertures of certain Polysyncraton spp (e.g. P. circulum Kott, 1962 ) although they are not arranged in the single circles found in the latter species. The number of vas deferens coils and the number of spicule rays are both relatively numerous for species of this genus. Leptoclinides imperfectus Kott, 1962 , and L. sulawesi Monniot F. and C., 1996 have seven coils of the vas deferens and are also distinguished from the present species by their chisel-shaped or truncated spicule ray tips. Further the latter species has fewer spicule rays and the former species has smaller spicules. Leptoclinides cavernosus Kott, 2001 has a similar number of spicule rays but the spicules are larger than those of the present species, the rays have chisel-shaped tips and it has only six coils of the vas deferens, and although L. seminudus Kott, 2001 has eight coils of the vas deferens its spicules are smaller with fewer rays and the lower half of its colony is aspicular.

Figures

Figure 16. Scanning electron micrographs of didemnid spicules: A, Atriolum tubiporum, QM G328004; B, Leptoclinides durus, QM G328158; C, Leptoclinides fungiformis, QM G328444; D, Leptoclinides vesica, QM G328458; E, F, Polysyncraton calculum, QM G328140; G, Polysyncraton dealbatum, QM G328119; H, Polysyncraton fistulum, QM G328446.