Lissoclinum polyorchis Monniot F., 1992

Monniot, Francoise, 2021, New records of deep-sea ascidians (Tunicata, Ascidiacea) from the New Caledonia region, Zootaxa 4996 (3), pp. 443-468 : 444

Lissoclinum polyorchis Monniot F., 1992

Figure 1

Station: Kanacono DW 4740. The colony, in pieces, was a crust hardened by dense calcareous spicules. The surface is flat and pieced by star like oral apertures ( Fig. 1A ). The colony is made of two layers separated by a wide common cloacal channel. The zooids hang vertically inside the cavity only linked to the both hard sheets of the tunic by a thin tissue covering a part of the thorax and abdomen. All tissues contain brown cells. The oral siphon is short with six lobes. The atrial aperture is wide, without languet. The lateral thoracic organs were not seen. There are four rows of stigmata obscured by sand particles filling the thoracic cavity. The abdomen is folded under the thorax. The gut loop is simple with a large stomach. The male gonad is a rosette of five testis vesicles placed against and below the gut loop. The sperm duct is straight. The ovary is present by a single oocyte close to the testis. During maturation the embryo discard from the abdomen in a pouch of the body wall and the fully developed tadpole become independent in a thin capsule of tunic partly included in the basal layer of the colony. The tadpoles are 1mm in diameter with a tail coiled in a half turn. They have three adhesive papillae separated by four pairs of vesicles ( Fig. 1B ). The internal structure is obscured by abundant brown cells but an otolith is obvious.

Lissoclinum polyorchis was already known from New Caledonia (Monniot F. 1992) but only off the barrier reef.

Figures

FIGURE 1. Lissoclinum polyorchis. A, part of a colony; B, larva, scale bar = 0.5mm.