Sigillina Savigny, 1816

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 261-262

Genus Sigillina Savigny, 1816

Sigillina cyanea ( Herdman, 1899) ( Fig. 47 )

Colella cyanea Herdman, 1899: 69 . Type locality: Australia, Port Jackson.

Sigillina cyanea – Kott 1990: 89, figs 9; 29, pl. 7, Australia.

MATERIAL EXAMINED. — Indonesia. Komodo Island, coll. Erhardt ( MNHN A3 SIG 11).

DESCRIPTION

Two deep, dark blue colonies 20 cm long each have a cylindrical head in continuity with the peduncle. The tunic’s general consistency is hard, and the superficial tunic is particularly resistant. The zooids open by unpigmented siphons placed close to each other. The body wall has a dark blue pigment. The thorax is wider than long, separated from the abdomen by a narrowing. The largest zooids measure 4 mm in length.

Both siphons are very short with six round lobes and a sphincter. No transverse muscles were seen on the thorax, but there are 15 to 18 longitudinal muscles on each side.

There are 12 oral tentacles in two orders along two different circles. A large unperforated space extends anteriorly as well as posteriorly to the branchial sac. The transverse vessels form high blades. We counted at least 30 stigmata in the first half row and 25 in the last half row. A brood pouch is appended to the postero-dorsal part of the thorax.

The drop-shaped abdomen is prolonged by a long, thin vascular appendage. The stomach is small and rounded, followed without constriction by a post-stomach that is slightly wider than the intestine. The anus opens by two lobes at the second stigmata row. The pyloric gland is a complex network of curved tubules and ampullae on the rectum at the stomach level. Several pyloric ducts converge towards the stomach, where they fuse. There is no pyloric vesicle.

The gonads are entirely located inside the gut loop below the stomach. The testis has about 30 follicles, almost all in a plane, each having a duct; these converge toward the centre of the testis to form a single common sperm duct, which follows the rectum. The ovary is central, with only a small oocyte in the examined colonies, which are mostly in the male phase.

A few larvae ( Fig. 47 ) are present between the zooids, close to the colony surface. They are large, up to 4 mm. They have the same dark blue pigment as the zooids in the surface epithelium, the visceral mass, and the ampullae around the adhesive papillae. The tail winds in less than a half-turn around the trunk ( Fig. 47A ). Two flat adhesive papillae are elongated and bilaterally compressed to form an anterior groove. On each side the adhesive papillae are lined by five or six digitiform ampullae. The larval branchial sac is very posterior, well-differentiated with three rows of numerous stigmata. There is an ocellus and an otolith.

REMARKS

This species does not show the structure of the adhesive papillae described by Kott (1990), but rather that described for Sigillina australis Savigny, 1816 . The type of the latter species (MNHN A3 SIG 2) is described as transparent with a reddish-brown colour.

Figures

FIG. 47. — Sigillina cyanea (Herdman, 1899), larva. Scale bar: 2 mm.