Ascidia sydneiensis Stimpson, 1855

Monniot, Françoise, 2018, Ascidians collected during the Madibenthos expedition in Martinique: 1 - Phlebobranchia, Zootaxa 4387 (3), pp. 451-472 : 462

Ascidia sydneiensis Stimpson, 1855

Fig. 10

Stations: AB 187; AB 189; AD 208; AM 0 5. (MNHN P5 ASC.A 432)

In the field A. sydneiensis is colorless or grey, often covered with epibionts or sediment and a dissection is necessary to identify the species as it may be confused with Ascidia interrupta . The Madibenthos specimens have a dull translucent tunic with irregular protuberances at the surface with varied epibionts. The body is attached by the left or the posterior side. The largest specimen collected is 5.5cm long. The oral siphon is apical with 8 lobes sometimes divided into multiple papillae. The anatomy is that described many times for specimens collected in the Pacific Ocean as well as in the Atlantic. The body wall has a light brown pigment. The dorsal tubercle is more or les convoluted. The dorsal lamina is long, prolonged far behind the oesophagus and with a smooth rim. There are no intermediate branchial papillae on the longitudinal vessels ( Fig. 10B ). The digestive tract occupies half of the left body side ( Fig.10A ). The secondary limb of the intestinal loop is inflated. The musculature ( Fig.10A ) of the right body side is characteristic with 2 bands of transverse fibres one ventral and one dorsal as figured in Monniot C. (1983) for a specimen from Guadeloupe. Muscles are absent on the left side.

Sydneiensis was first described from the Pacific Ocean where it is very common and found again everywhere in warm seas. In the western Atlantic the first record is that of Van Name (1930) and a full description is given by Van Name (1945). Gravier (1955) cites this species in Martinique. Several records concern the Brazilian coast ( Rodrigues, Rocha & Lotufo 1998, Bonnet & Rocha 2011).

Figures

FIGURE 10. Ascidia sydneiensis.A, body stained dissection (Scale bar = 1cm); B, part of the branchial tissue.