Polycarpa stirpes Kott, 1985

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 333

Polycarpa stirpes Kott, 1985

( Figs 97 ; 129B)

Polycarpa stirpes Kott, 1985: 202 , fig. 95, Queensland, Indonesia, and Philippines, and synonymy. — Monniot C. 1987b: 278, fig. 1C, D, New Caledonia.

MATERIAL EXAMINED. — Philippines. W Luzon, Zambales, Masinloc town, Luan Island, 15°29.90’N, 119°54.44’E, 7 m, 4. V.1995 ( MNHN S1 POL.B 383).

DESCRIPTION

This species, 3.5 cm tall by 2.5 wide by 2 cm thick, is erect, fixed by the posterior part of the left side. The tunic is covered with epibionts (Fig. 129B) and is difficult to see on the substrate. The square siphons have white spots, which can fuse to make a line. The inner tunic of the siphons is flesh-coloured. The tunic is tuberculated, internally white. Its thickness varies from 1 to 3 mm and it is soft.

The body wall is yellow and remains the same colour after formalin fixation. It is 0.5 mm thick. It contains whitish granules but remains translucent, and one can see the gonads through it. The musculature is not very welldeveloped. Both siphons have a large, thin velum, easily torn. The oral tentacles are insert- ed in the bottom of the siphon, almost in contact with the prepharyngeal band. There are 12 long tentacles in two or three orders and one to three very small tentacles between them ( Fig. 97D ). The prepharyngeal band has a single crest, which is not wavy at the level of the branchial folds. It curves in a pronounced dorsal V, which is prolonged by a medio-dorsal pad anterior to the beginning of the dorsal lamina. The fold on each side ends at the level of this crest. The dorsal tubercle is U-shaped ( Fig. 97D ), dug into the body wall rather than protruding. The dorsal lamina progressively increases posteriorly in height; it ends obliquely cut at the middle of the oesophagus entrance. The branchial sac has four round, high folds. We counted:

R. E. 3 7 4 13 4 12 2 7 4

D.L. 2 7 3 13 4 12 3 10 3 E. L.

The folds progressively lessen and disappear at the oesophagus entrance. The first longitudinal vessel on the right side is thicker than the others; it joins posteriorly the vessels and forms a pseudo-fold in the posterior part of the body. It moves away from the dorsal lamina posteriorly; anteriorly we counted six to seven stigmata in this dorsal space and more than 30 stigmata at the oesophagus entrance. The longitudinal vessels are high. The meshes contain 10 to 12 elongated stigmata between the folds and an average of six on the folds. Parastigmatic vessels only appear where a stigmata row divides.

The gut, a closed loop, is located in the posterior third of the left side ( Fig. 97B, C ). The stomach is slightly enlarged with 16 clearly marked internal grooves. The external wall is smooth. There is a small caecum. The intestine draws a regular curve, the rectum is short, and the anus lobed. A large endocarp occupies the centre of the intestinal loop, and two smaller ones lie between the oesophagus and the intestine ( Fig. 97C ).

The gonads are included in the thickness of the body wall. The central ovary is encircled by a crown of testis follicles. The sperm ducts converge in a non-protruding papilla that opens near the female papilla ( Fig. 97E ).

A ring of small tentacles encircles the cloacal siphon ( Fig. 97C ).

REMARKS

This inconspicuous species, by its anatomy, is closely allied to P. argentata ( Sluiter, 1890) . The species differ essentially in the gonad disposition: ventral in P. argentata and located in the centre of the lateral body wall in P. stirpes . In their external appearance these species are very different, as well.

Figures

FIG. 97. — Polycarpa stirpes Kott, 1985; A, B, right and left sides of a specimen; C, specimen ventrally opened; D, dorsal tubercle; E, polycarp. Scale bars: A, B, 5 mm; C, 2 cm; D, E, 0.5 mm.