Pyura mozambica, Monniot, 2002

Monniot, Claude, 2002, Stolidobranch ascidians from the tropical western Indian Ocean, Zoological Journal of the Linnean Society 135 (1), pp. 65-120 : 100-102

PYURA MOZAMBICA SP. NOV. ( Fig. 28 )

Material

Holotype: MNHN S2 PYU 402 , tunic, body on microscope slides S2643–644, Mozambique: Ibo Island , coll. C. Monniot, 1995.

Description

The single specimen is spherical, 12 mm in diameter. The tunic is red, hard and thick. Its surface is irregularly corrugated, with bumps that are more defined around the siphons. The siphons are sessile. The thin body wall reveals the internal organs in transparency. The musculature comprises strong sphincters at the siphons and radiating ribbons, strong and regularly spaced at their origin and dividing down the sides of the body into thinner fibres that reach the medioventral line.

There are a dozen long oral tentacles with only short first order ramifications, intercalated with some much shorter tentacles with lateral buttons, and between them one or two orders of very small tentacles that are not ramified. The prepharyngeal band has two equal rims. It curves in a dorsal V and extends as a groove at the start of the dorsal lamina.

The dorsal tubercle, flat and discoid, opens anteriorly in a C ( Fig. 28A ).

The branchial sac has six high, wide folds on each side, each with 13–15 longitudinal vessels; the folds are separated from each other by two vessels. The folds are not well delimited. There are parastigmatic vessels. The dorsal lamina is made of long denselypacked languets.

The digestive tract makes a wide loop on most of the left side of the body ( Fig. 28A ). The hepatic gland is divided into several lobes along half of the ascending limb of the gut ( Fig. 28A ). The anus is gaping with a smooth rim that is not rolled.

There is a voluminous gonad on each side ( Fig. 28B,C ), the left one totally included in the gut loop ( Fig. 28A ). The right gonad is ventral, parallel to the endostyle. In each gonad, the ovary is made of regularly spaced lobes perpendicular to a straight axial part. On the top of each ovarian lobe a few testis vesicles make a cap ( Fig. 28D ). Each testicular element produces a duct joining a common sperm duct that runs along the surface of the ovarian axis. Male and female papillae are united.

The internal layer of the body wall is covered with numerous, more-or-less elongated endocarps, as well as with the gonads and gut ( Fig. 28A ).

The cloacal siphon’s internal opening is surrounded by a network of large ramified tentacles.

This new species differs from congenerics mainly by the large number of its endocarps and the very large and branched cloacal tentacles.

Etymology

The species name refers to the geographical origin of the species.

Figures

Figure 28. Pyura mozambica sp. nov.: A, body ventrally opened. B,C, both sides of the body, the tunic removed. D, part of a gonad. Scale bars: A,B,C = 5mm, D = 1mm.