Eudistoma Caullery, 1909

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 237-238

Genus Eudistoma Caullery, 1909

Eudistoma album Monniot F., 1988 ( Fig. 116D )

Eudistoma album Monniot F., 1988: 210 , fig. 6a-c. Type locality: New Caledonia.

MATERIAL EXAMINED. — Tonga. Tongatapu Lagoon, E side, Alaki, 21°09.87’S, 175°08.33’W, 1 m, 22.XI.1997 ( MNHN A3 EUD 201).

Mariana Islands. Guam, South of Pati Point, 10 m, coll. Paulay( MNHN A3 EUD 218).

DESCRIPTION

The colonies have a very characteristic pearly colour when alive ( Fig. 116D ) but become black when preserved in formalin. They are pedunculate with round heads. The common base of the lobes and the peduncles are incrusted with sand. There are no systems. The colorless zooids protrude slightly at the colony surface. Both siphons are at the same level. The thoracic musculature is strong. The abdomen, much longer than the thorax, has a posterior stomach. The rectum makes a curve at the level of the stomach in the most relaxed zooids. The male follicles are grouped at the base of the gut loop and the ovary is lateral to them. The larvae are small, 350 µm in length, incubated in small numbers in the cloacal cavity. They have three adhesive papillae alternating with four pairs of ampullae.

REMARKS

The iridescent white colour of the colonies in life is particularly characteristic. This species, described from New Caledonia, is recollected for the first time. Its presence in Guam and Tonga at very shallow depth suggests a more extensive distribution in the western Pacific.

Figures

FIG. 116. — A, Clavelina robusta Kott, 1990; B, Citorclinum laboutei Monniot F. & Millar, 1988; C, Cystodytes hapu Monniot C. & Monniot F., 1987; D, Eudistoma album Monniot F., 1988; E, Eudistoma fluorescens n. sp.; F, Eudistoma fucatum n. sp.