Lissoclinum textile, Monniot & Monniot, 2001

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 285-286

Lissoclinum textile n. sp.

( Figs 67B ; 68 ; 122F )

TYPE MATERIAL. — Papua New Guinea. Louisiade Archipelago, Calvados Island Chain, Brooker Channel, 11°03.09’S, 152°28.62’E, 12 m, 1. VI.1998 ( MNHN A2 LIS 163).

ETYMOLOGY. — From the Latin textile : cloth.

DESCRIPTION

The thin white crusts have a lobed outline, and a smooth surface with a design of brown lines drawing polygonal meshes ( Fig. 122F ) (hence the species name). The brown pigment cells are distributed exclusively in the surface layer above the common cloacal channels; the zooids line each side of the channels and are absent from the centre of the meshes. The whole tunic is filled with spicules but the colonies remain soft. The zooids, which have their abdomens folded under the thorax, occupy only the upper half of the colony’s thickness of the colony. The oral siphon is short and narrow ( Fig. 68A ). The cloacal aperture is moderately large, without a languet. The round lateral thoracic organs form cups, at the level of the second row of stigmata, near the endostyle.

The branchial sac has a square shape with 12 stigmata in the first half row and 10 in the fourth half row. There is no retractor muscle.

The abdomen ( Fig. 68B ) is difficult to find as it is embedded in a body wall filled with reserve cells. The gut loop is flat with neatly separated compartments ( Fig. 68B ). There are up to five well-separated testis follicles in a rosette, their ducts joining in a straight common sperm duct. The ovary lies against the testis.

Only one larva was found in the three colonies examined, located in a cloacal channel and protruding at the colony surface. It is large, 1.3 mm for the trunk ( Fig. 68C ). There are three adhesive papillae, and five ampullae on each side. The larval body wall is filled with reserve cells. An ocellus and otolith are present.

The stellate spicules ( Fig. 67B ), 80 µm in diameter, are made of numerous thin needles.

REMARKS

Lissoclinum species having several testis follicles are not common. L. textile n. sp. is closely allied to the New Caledonian species L. polyorchis Monniot F., 1992 , with the same number of stigmata, no cloacal languet, no retractor muscle, and several testis lobes. But Lissoclinum polyorchis has a large cloacal opening, only four pairs of ampullae alongside the larval adhesive papillae, and its spicules are different in shape. As well, the colonies in that species lack the surface design with brown meshes characteristic of L. textile , and the disposition of the zooids in the colony is different.

Figures

FIG. 67. — Spicules; A, Lissoclinum guinense n. sp.; B, Lissoclinum textile n. sp. Scale bars: 10 µm.

FIG. 68. — Lissoclinum textile n. sp.; A, thorax; B, abdomen; C, larva. Scale bar: A, B, 0.25 mm; C, 0.5 mm.

FIG. 122. — A, Diplosoma redika Monniot F., 1994; B, Diplosoma versicolor Monniot F., 1994; C, Lissoclinum abdominale Monniot F., 1983; D, Lissoclinum guinense n. sp.; E, Lissoclinum taratara Monniot C. & Monniot F., 1987; F, Lissoclinum textile n. sp.