Ascidia archaia Sluiter, 1890

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 304-306

Ascidia archaia Sluiter, 1890

Ascidia archaia Sluiter, 1890: 346 , figs 21-23. Type locality: Indonesia. Synonymy: see Monniot C. & Monniot F. 1987: 92, fig. 34, Polynesia. — Monniot C. 1987a: 7, New Caledonia.

MATERIAL EXAMINED. — Palau. Koror, Malakal Harbour, Buoy #1, 7°19.88’N, 134°27.50’E, 1 m, 28.I.1998 ( MNHN P5 ASC.A 315).

REMARKS

This species is common in fouling communities of tropical Indo-Pacific and Atlantic coasts.

Ascidia gemmata Sluiter, 1895 s.l. ( Figs 80 ; 125D )

Ascidia gemmata Sluiter, 1895: 177 , pl. 9, figs 7-9. Type locality: Indonesia. — Tokioka 1950: 131, fig. 11, pl. 9; fig. 2, Palau; 1952: 103, fig. 169, Port Moresby; 1967: 140, fig. 51, Mariana, Carolina and Wake Islands. — Nishikawa 1984: 126, Micronesia; 1986: 52, Micronesia; 1991: 142, fig. 14, Japan Sea.

? Ascidia gemmata – Hartmeyer & Michaelsen 1928: 292, fig. 8, NW Australia. — Kott 1985: 37, fig. 10e-i, Australia. — Monniot C. 1991a: 507, fig. 7, New Caledonia.

MATERIAL EXAMINED. — Palau. Coll. Faulkner ( MNHN P5 ASC.A 297). — Mecherchar, Jellyfish Lake, marine lake, on mangrove roots, 7°09.83’N, 134°22.50’E, 1 m, 8. VI.1994 ( MNHN P5 ASC.A 296).

DESCRIPTION

The largest individual measures 4 × 2.5 × 1 cm. It was erect and attached by 2/3 of its left side. The oral siphon is terminal. The cloacal siphon is in the middle of the body, displaced to the right side in one specimen, directed backwards in the others ( Fig. 80A, B ). Both siphons are wide. We counted eight low lobes on the oral aperture and six to eight on the cloacal siphon. The tunic is devoid of epibionts. In life this species is pinkish ( Fig. 125D ). The colour is concentrated in the body wall, in more numerous patches dorsally. The oral siphon has eight darker stripes and the cloacal lobes have white spots. When fixed in formalin the tunic is translucent and has a solid consistency. It contains a network of anastomosed blood vessels ending in small ampullae just under the surface, corresponding to small surface papillae. Numerous cells fill the vascular network.

The musculature, made up of thin fibres, makes a complete network on the right side ( Fig. 80B ) but only covers the anterior part of the body on the left side ( Fig. 80A, F ). There is a large oral velum that is easily removed. There are about 60 oral tentacles, shorter than the oral siphon. They are planted at the same level around a circle at the base of a protruding crest, in three orders of size. Some very small ones are more numerous ventrally. The prepharyngeal band has two equally high rims. The dorsal curve is only slightly marked ( Fig. 80E ). The prepharyngeal area has small papillae. The dorsal tubercle is small, only slightly protruding, and with a U-shaped slit ( Fig. 80E ). The neural ganglion is distant from the dorsal tubercle by four to five times its length; for a specimen 4 cm in length, this distance corresponds to 7 mm. The dorsal lamina is doubled for half the distance between the dorsal tubercle and the ganglion. In its middle length, it consists of a high blade with ribs on each side ending in long teeth. At the oesophagus entrance, it is abruptly lowered and transformed into a low crest extending down to the bottom of the branchial sac. In one specimen it is reduced to just the languets. On the right side, at the oesophagus entrance, the branchial papillae close to the dorsal lamina are twice the height of papillae elsewhere but are not linked by a lamina.

The branchial tissue is pleated. It extends slightly beyond the base of the intestinal loop. At the level of the top of the intestinal loop there are about 40 longitudinal vessels on the left side and a few more (46) on the right side. The papillae are large, antero-posteriorly flattened without lateral protrusions. The branchial meshes are transversally elongated with eight to 12 stigmata each. There are no parastigmatic vessels and no intermediate papillae.

The massive gut, with a thin and transparent wall, makes a double closed loop ( Fig. 80C, D ). The stomach has irregular internal folds. The posterior intestine is dilated. The anus has a plain rim.

The ovary is massive, exclusively located in the primary intestinal loop. The testis spreads in a thin layer on the intestine ( Fig. 80C, D ). The genital ducts follow the rectum and open in slits beside the anus. The female aperture is wide. Large renal accumulation vesicles lie in the posterior part of the intestinal loop, particularly obvious on the external side ( Fig. 80C ). The voluminous heart does not contain inclusions.

REMARKS

The specimens in this collection certainly correspond to what Tokioka (1950) described from the Palau Islands under the name Ascidia gemmata . The only difference with our sample is the clearly posterior position of the cloacal siphon in Tokioka’s specimens. The shape of the gut is the same with a marked enlargement of the posterior intestine and a short rectum opening well below the top of the intestinal loop. Tokioka and Nishikawa both figured variable dorsal tubercles, often with multiple openings, but this is not the case in our specimens.

Several authors have described A. gemmata , and the descriptions vary. All mention a posterior cloacal siphon opening backwards, but the gut shape varies. Sluiter (1895) depicts the gut with an enlarged intestine and a short rectum. Tokioka describes the same shape (1950) at Palau, (1952) in New Guinea, and (1967) in the Mariana, Carolina and Wake Islands. Nishikawa (1991) shows a short rectum for the Japanese specimens. In Australia, Hartmeyer & Michaelsen (1928) figure a longer rectum without dilation. This same appearance is reported by Kott (1985) in Australia and Monniot C. (1991a) in New Caledonia. In the Australian and Caledonian specimens, the ovary projects out of the primary gut loop. These specimens perhaps represent a distinct species, but the variability of A. gemmata is not sufficiently known to say so.

Figures

FIG. 80. — Ascidia gemmata Sluiter, 1895 s.l.; A, B, left and right sides of the body; C, D, both sides of the gut; E, dorsal area; F, left side of the largest specimen. Scale bars: A-D, F, 1 cm; E, 2 mm.

FIG. 125. — A, Perophora modificata Kott, 1985; B, Perophora namei Hartmeyer & Michaelsen, 1928; C, Ecteinascidia bandaensis Millar, 1975; D, Ascidia gemmata Sluiter, 1895 s.l.; E, Ascidia ornata n. sp.; F, Ascidia sydneiensis Stimpson, 1855.