Polycarpa arnoldi ( Michaelsen, 1914 )

Monniot, Françoise, 2018, Ascidians collected during the Madibenthos expedition in Martinique: 2. Stolidobranchia, Styelidae, Zootaxa 4410 (2), pp. 291-318 : 303

Polycarpa arnoldi ( Michaelsen, 1914) .

Fig. 11

Pandocia arnoldi Michaelsen, 1914 : Annobon, Guinea.

Polycarpa arnoldi: Van der Sloot 1969 and synonymy; Goodbody 1984; Monniot C. 1983; Monniot C. & F. 1994; Rocha et al. 2012.

Stations: AB 102; AB 356; AB 400; AD 111; AD 208; AD 209. (MNHN S1 POL.B 581)

The body is ovoid in a soft tunic more or less covered with epibionts and sediment. The body wall is transparent with a thin muscular network and some stronger fibres issued from the siphons ( Fig. 11A ). Both siphons have a large velum ( Fig. 11A ). The oral tentacles are thin and numerous in 3 sizes. The dorsal tubercle opens in a C with horns sometimes rolled. There are no papillae on the prepharyngeal area. The dorsal lamina with a plain edge becomes higher posteriorly. There are 4 high branchial folds on each side ( Fig. 11B ). One formula is:

E -3 (13) 3 (5) 3 (13) 3 (12) 2 - DL- 2 (9) 3 (12) 3 (15) 3 (12) 3 - E

There are parastigmatic vessels. The alimentary canal is attached to the body wall by trabeculae. The stomach is pear shaped with oblique folds and a caecum. The intestine in a closed loop contains a round endocarp ( Fig.11A ); there are no endocarps on the body wall. The anus has 8 lobes. The gonads are numerous on each side with a characteristic shape ( Fig. 11A ). The round polycarps are distributed along transverse lines ( Fig. 11A ). Each contains a central ovary partially encircled by testis vesicles. The sperm ducts converge to the polycarp centre and unite in a short tube protruding in the atrial cavity. A circle of thread-like tentacles lies at the base of the atrial velum.

First described from the eastern Atlantic by Michaelsen (1914), P. arnoldi was found again in this region from Cabo Verde (MNHN collection). It has been recorded several times in the Western Atlantic (Van der Sloot 1969; Monniot C. 1983; Rocha et al 2012) but was also found in the Indian Ocean ( Monniot C. 2002)

Figures

FIGURE 11. Polycarpa arnoldi stained.A, body ventrally opened, scale bar = 5mm; B, branchial sac.