Leptoclinides durus Kott, 2001

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 : 1167-1168

Leptoclinides durus Kott, 2001

( Figure 16B )

Leptoclinides durus Kott 2001, p. 57 .

Distribution

Previously recorded (see Kott 2001): Western Australia (Bonaparte Archipelago); Queensland (Great Barrier Reef -Heron I. and north to Hinchinbrook, Deloraine I. and Dingo Reef); Arafura Sea, Micronesia. New record: Western Australia CSIRO SS10/05 (Bunbury, Stn 14, 95 m, 20.11.05, QM G328158).

Kott (2001) noted that the species was not common in waters less than 6 m deep.

Description

The newly recorded colony is top-shaped, rounded terminally and tapering to an almost pointed base where it appears to have been attached to the substrate. Two small wart-like protuberances on the upper rounded surface may be common cloacal apertures, but common cloacal canals or cavities were not detected. The test is packed with spicules that are especially crowded in the surface at branchial level. Spicules are small, to 0.03 mm diameter. Some are stellate with 11–13 conical rays in optical transverse section but the larger ones have stumpy rays and are almost globular. Zooids, in a single layer at the surface, are relatively small, underdeveloped and appear to be in vegetative phase, with both thoracic and oesophageal buds being present. The distal end of the gut loop is flexed ventrally to form a double loop. Four or five male follicles are in the abdomen and the vas deferens makes an Sshaped curve across their outer surface.

Remarks

Zooids of this specimen are small and contracted and although it has been assigned to the ‘‘ dubius ’’ group the only characters of that group detected are the double gut loop, S-shaped curve of the vas deferens over the outside of the testis and the particularly small spicules (smaller than those usually found in the genus). The characters that distinguish the present species from others in the group are the spicules crowded throughout the colony rather than being in a layer at the surface. The absence of a large grape-like cluster of male follicles in the newly recorded colony may be associated with its immaturity. The upright top-shaped (rather than a sheet-like) colony (see Kott 2001) could reflect some intra-specific variation. The number of spicule rays found in the present specimen appears to be the same as the number in the scanning electron micrographs for this species shown in Kott (2001), and Kott’s estimate of 9–11 rays in optical transverse section appears to be too low.

Leptoclinides dubius has a similar (but greater) diversity of spicules. Also, unlike the present species, spicules are confined to the surface and basal layers of test.

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.