Pseudodistoma megalarva Monniot F. & Monniot C., 1996

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 227

Pseudodistoma megalarva Monniot F. & Monniot C., 1996

Pseudodistoma megalarva Monniot F. & Monniot C., 1996: 147 , fig. 6F, J, pl. 2A. Type locality: Indonesia. MATERIAL EXAMINED. — Palau. Koror, West Uchelbeluu Reef, Short Dropoff, 7°16.51’N, 134°31.55’E, 10 m, 12.VIII.1996 (MNHN A1 PSE 38). — Siaes tunnel, west barrier reef, 7°18.76’N, 134°13.50’E, 3 m, 22.XII.1997 (MNHN A1 PSE 48).

Pseudodistoma novaezelandiae ( Brewin, 1950) ( Figs 20 ; 114F )

Sigillinaria novaezelandiae Brewin, 1950: 534 . Type locality: New Zealand.

Pseudodistoma novaezelandiae – Millar 1982: 44.

MATERIAL EXAMINED. — Papua New Guinea. Louisiade Archipelago, Conflict Group, 10°43.52’S, 151°44.54’E, 40 m, 29. V.1998 ( MNHN A1 PSE 54). — Coral Sea, eastern fields, 10°02.22’S, 145°33.01’E, 23 m, 14. VI.1998 ( MNHN A1 PSE 53).

DESCRIPTION

The colonies form elongate, ovoid stoutly pedunculate lobes arising from a common base. The sand-free tunic is opaque, brown ( Fig. 114F ) or dark grey with white perisiphonal patches. There are no systems. The thoraces lie perpendicular to the colony surface, both siphons opening near each other. The abdomen and very long postabdomen lie parallel to the lobe’s long axis. The post-abdomen is so long that the zooid may reach 5 cm. Both siphons have six lobes ( Fig. 20A ). The thorax is wider than high. There are three rows of numerous stigmata. We counted about 20 longitudinal muscles on each side, regularly spaced.

The abdomen ( Fig. 20A ) is longer than the thorax and has a long oesophagus. The stomach has a smooth wall or four folds. The post-abdomen is particularly long and contains the gonads in its very posterior part, with the ovary immediately anterior to the testis follicles ( Fig. 20B ).

The larvae are incubated in a dilated pouch of the cloacal cavity, without peduncle.

The larval trunk measures 0.72 mm. It has three large adhesive papillae in a line, each encircled by a cup-shaped structure made of thin lamellae ( Fig. 20C ).

REMARKS

This species is characterised by its larvae and by the opaque and pigmented tunic of the pedunculate lobes of the colony. It has been known only from the north of New Zealand.

Figures

FIG. 20. — Pseudodistoma novaezelandiae (Brewin, 1950); A, B, two parts of a zooid; C, D, abdomen; E, larva. Scale bars: A-D, 1 mm; E, 0.5 mm.

FIG. 114. — A, Monniotus papillosus n. sp.; B, Polyclinum psammiferum Hartmeyer, 1911; C, Pseudodistoma aureum (Brewin, 1957); D, Pseudodistoma digitata n. sp.; E, Pseudodistoma fragile Tokioka, 1958; F, Pseudodistoma novaezelandiae (Brewin, 1950).