Leptoclinides reticulatus ( Sluiter, 1909 )

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 288-290

Leptoclinides reticulatus ( Sluiter, 1909)

Didemnum reticulatum Sluiter, 1909: 60 . Type locality: Indonesia.

Leptoclinides reticulatus – Monniot F. & Monniot C. 1996: 178, figs 23; 24B, pl. 4B, Palau.

MATERIAL EXAMINED. — Indonesia. N Sulawesi, West of Manado, 1°23.52’N, 124°32.64’E, 10 m, 14. V.1993 ( MNHN A2 LEP 77).

Palau. Koror, Ngederrak Reef along Ngel Channel, seagrass bed, 7°17.90’N, 134°28.34’E, 1 m, 27.XI.1996 ( MNHN A2 LEP 78).

Leptoclinides subviridis ( Sluiter, 1909) ( Figs 71 ; 123C )

Leptoclinum subviridis Sluiter, 1909: 81 , pl. IV, fig. 9. Type locality: Banda Sea.

MATERIAL EXAMINED. — Philippines. Mindanao, Davao, SW of Samal Island, W side of Talikud Island, 6°56.11’N, 125°40.46’E, 3 m, 31.III.1996 ( MNHN A2 LEP 82).

DESCRIPTION

The colonies were not abundant but they were found in several places. They form low cushions of a rubbery consistency, 1 cm thick and 5 to 8 cm across. The surface of the colony is raised in convoluted ridges between hollows and furrows into which the oral apertures open ( Fig. 123C ). This shape reminds one of the didemnid Lissoclinum patella ( Gottschaldt, 1898) . The colour is pale grey, slightly translucent, with dark spots that are probably symbiotic organisms gathered in balls in the surface layer of the colony. Rare elongated and dendritic pigment cells are scattered in the tunic. No trace of spicules could be found in any part of the vacuolated tunic.

The common cloacal cavity is large, interrupted only by some pillars of tunic uniting the upper part of the colony, which contains the zooids and larvae, to the basal layer. This wide cavity opens at the colony surface by a few wide holes.

The zooids have a large thorax ( Fig. 71A ) and a much smaller abdomen ( Fig. 71B, C ), either folded under the thorax or in a straight line according to the zooid distribution in the colony. The oral siphon has occasionally six undulations but no true lobes, and a weak sphincter. There are a dozen irregular oral tentacles. The cloacal tube is long and wide with a plain edge. The thoracic musculature is weak with about 15 very thin, regularly spaced longitudinal fibres. Fourteen to 16 elongated stigmata constitute the first branchial half row. The lateral thoracic organs and a retractor muscle are absent.

The waist is narrow. The gut makes a closed loop ( Fig. 71B, C ). The only well-marked compartment is the stomach. The anus opens next to the oesophagus entrance. The testis is made of a flat rosette of six to eight lobes applied to the gut loop, and the sperm duct is coiled in five to six turns above it ( Fig. 71B ). The ovary lies against the testis, and also on the stomach.

The larvae ( Fig. 71D ) develop in the tunic close to the abdomens. They are almost spherical with an already well-developed branchial sac. The three adhesive papillae are stout and short ( Fig. 71D ). Beside them are four pairs of ampullae or sometimes six pairs resulting from a division at an advanced stage. The larvae are not gemmiparous.

REMARKS

This species differs from any other Leptoclinides in its total absence of spicules and lateral thoracic organs, a colony whose surface is raised in ridges, and a spacious basal common cloacal cavity opening at the colony surface by wide holes. The presence of symbiotic cells is also characteristic.

These samples correspond well to the type specimen (ZMA TU 595 from Banda Sea), which has the same zooid anatomy, a vascular tunic without spicules, and a thick colony. The type colony lacks larvae.

Figures

FIG. 71. — Leptoclinides subviridis (Sluiter, 1909); A, thorax; B, C, abdomens; D, larva. Scale bar: 0.5 mm.

FIG. 123. — A, Atriolum robustum Kott, 1983; B, Leptoclinides madara Tokioka, 1953; C, Leptoclinides subviridis (Sluiter, 1909); D, Diazona formosa Monniot F. & Monniot C., 1996; E, Diazona fungia n. sp.; F, Diazona pedunculata n. sp.