Polycarpa nigerrima, Monniot & Monniot, 2001

Monniot, Françoise & Monniot, Claude, 2001, Ascidians from the tropical western Pacific, Zoosystema 23 (2), pp. 201-383 : 327-329

Polycarpa nigerrima n. sp.

( Fig. 128E )

Polycarpa nigricans – Monniot C. 1987b: 286, fig. 5, New Caledonia. — Monniot C., Monniot F. & Laboute P. 1991: 217. — Monniot F. & Monniot C. 1996: 258. — Kott 1985 part, pl. 3f.

TYPE MATERIAL. — New Caledonia. Barrier reef, coll. Monniot ( MNHN S1 POL.B 424).

ETYMOLOGY. — From the Latin niger : black.

OTHER MATERIAL EXAMINED. — Papua New Guinea. Coral Sea, Eastern Fields, 10°01.02’S, 145°38.66’E, 9 m, 14.VI.1998 (Sample: CRRF).

DESCRIPTION

The specimens, arrayed in clusters, are joined at their base. They are entirely black except for a pale line at the rim of the siphons ( Fig. 128E ). They are 2 cm in length and carry some epibionts. The black tunic is firm and thick. The dark brown body wall is also thick. The oral tentacles, regularly alternated in three orders of size, lie far forward in the oral siphon. The dorsal tubercle lies in the V of the prepharyngeal band, its aperture making a C opened on the right side. The dorsal lamina is very long. The branchial sac is dark brown; it has four well-spaced folds.

The gut has a posterior position. It forms a closed loop in which there are two endocarps. The pyloric caecum is very small. The anus has numerous round, thick lobes.

The gonads are included in the thickness of the body wall, and only the genital papillae poke out, but the polycarps make swellings on the internal body wall. There is a cloacal velum with a ring of thin cloacal tentacles.

REMARKS

In 1996, Monniot F. & Monniot C. pointed out that there were several species confused under the name Polycarpa nigricans . They isolated one species under the name Polycarpa tokiokai Monniot F. & Monniot C., 1996 , from Polycarpa nigricans Heller, 1878 s.s., the latter now strictly an ascidian from the Indian Ocean. And they separated but did not name a third species, comprising some Pacific Ocean populations.

The new collection allows us to confirm that P. nigerrima n. sp. is effectively different from P. nigricans , and exactly corresponds to the description given by C. Monniot (1987b: 286, fig. 5).

The new species includes none of the specimens collected in the Indian Ocean which belong to P. nigricans Heller, 1878 . In the Pacific two different but closely allied species coexist. These are P. nigerrima n. sp. and P. tokiokai Monniot F. & Monniot C., 1996 from Palau and Indonesia, including material described by Monniot C. & Monniot F. 1987, under the name P. nigricans from the Philippines. Kott (1985: 174) has mixed all three species under the name P. nigricans .

Polycarpa papillata ( Sluiter, 1885) ( Figs 94 ; 128F )

Styela (Polycarpa) papillata Sluiter, 1885: 192 . Type locality: Indonesia.

Polycarpa papillata – Kott 1985 part, pl. IIIg, Queensland.

Non Polycarpa papillata – Monniot C. 1987b, New Caledonia. — Monniot F. & Monniot C. 1996, Papua New Guinea.

MATERIAL EXAMINED. — Indonesia. Komodo Island, coll. Erhardt.

DESCRIPTION

The specimens are erect, the largest 8 cm in height and 3.5 cm in diameter with the siphons 2.5 cm apart. Both siphons are large with four lobes and four longitudinal red stripes ( Fig. 128F ). Some other red patches occur on the naked white tunic, and are present throughout its thickness. There is a dense transverse musculature in the external layer of the body wall and, on the oral siphon, external longitudinal muscular bundles.

There is no oral velum. Sixteen oral tentacles in three orders of size are well-spaced over a muscular ring. The prepharyngeal band has two blades. It curves in a dorsal V prolonged by a groove 2 mm long. The dorsal tubercle is simple, slightly protruding, with a U-shaped opening with inwardly curved horns ( Fig. 94 ). The dorsal lamina is a low membrane ending before the oesophagus entrance. The endostyle is long, encircling the posterior extremity of the body to reach the oesophagus entrance four fifth of the way down the body length. Thus, the branchial sac forms a pouch posterior to the oesophagus. The four high branchial folds overlap each other. The right side formula is: R.E. 7 15 6 18 4 20 7 17 4 D.L.

The folds end without papillae around the oesophagus entrance. The first fold on the right side is parallel to the dorsal lamina. The space between the dorsal lamina and the first longitudinal vessel does not widen posteriorly.

The gut forms a closed loop, very loosely attached to the body wall ( Fig. 94 ). The oesophagus is short; the stomach has numerous low ridges. Many finger-like lobes surround the anus. The polycarps are oval, scattered on both sides of the internal body wall, more numerous on the right side than on the left side ( Fig. 94 ). There are no polycarps posterior to the gut on the left side. The endocarps are very numerous, round except in an area posterior to the stomach where they are elongated ( Fig. 94 ).

The internal surface of the cloacal siphon is covered with papillae.

REMARKS

Specimens from New Caledonia and Papua New Guinea were erroneously assigned to P. papillata by Monniot C. (1987b) and Monniot F. & Monniot C. (1996), and are now identified as a new species, Polycarpa reviviscens .

Kott (1985) describes a large variability in P. papillata , with different sizes of the specimens, different colours, and variations in the internal anatomy. The variability that she attributes to P. papillata corresponds to at least three species; the large P. papillata ( Sluiter, 1885) with red marks on the tunic, P. captiosa ( Sluiter, 1885) recorded from Indonesia (Monniot F. & Monniot C. 1996: 249, fig. 53) which has a complex dorsal tubercle and gonads in lines, and the smaller P. reviviscens n. sp., with aggregated individuals, a dorsal tubercle with a U-shaped opening, less numerous polycarps, and a posterior extension of the body wall on the left side.

Figures

FIG. 128. — A, Polycarpa argentata (Sluiter, 1890); B, Polycarpa camptos n. sp. covered by a black didemnid; C, Polycarpa captiosa (Sluiter, 1885); D, Polycarpa cryptocarpa (Sluiter, 1885); E, Polycarpa nigerrima n. sp.; F, Polycarpa papillata (Sluiter, 1885).

FIG. 94. — Polycarpa papillata (Sluiter, 1885). Scale bar: 1 cm.