Aplidium boucheti, Monniot, Françoise, 2012

Monniot, Françoise, 2012, Some ascidians from the southern coast of Madagascar collected during the “ AtimoVatae ” survey, Zootaxa 3197, pp. 1-42 : 5-6

Aplidium boucheti n. sp.

( Figures 3 , 4A )

Etymology. dedicated to Philippe Bouchet chief scientist of the Atimo Vatae survey

Station. TA 12 (MHNH A1 APL.B 553, holotype)

In a cushion 4cm in diameter and 2.2cm thick ( Fig. 4A ), the colony was attached along its whole base. The colour in life was probably red and turned brown in formalin. The circular systems are obvious according to the absence of sand grains around the common cloacal apertures. The incrustation of sand is limited to the colony surface and the basal layer. Rare particles are found between the zooids into the soft and transparent tunic. The zooids, in regular rings, occupy the whole thickness of the colony by their long post-abdomen. They are pigmented in red. The oral aperture has 6 lobes. The atrial siphon has an uncommon structure ( Fig. 3 A,F). A simple languet arises from the dorsal side of the aperture. In addition a thread-like languet prolongs the posterior rim of the siphon. Another languet protrudes from the dorsal body wall behind the atrial siphon. The musculature is made of 5 longitudinal muscle fibres limited to the thoracic half length. There are 12 to 13 rows of stigmata ( Fig. 3 B). The gut loop ( Fig. 3 C,E) is wide with well separate segments. The oesophagus is slightly inflated in its middle part. The stomach is asymmetrical with more than 20 folds ending in sharp tips at the oesophagus entrance. The annular post-stomach is followed by an ampulla. The rectum begins with caeca. The ovary is at some distance from the gut. The testis vesicles occupy the first half length of the post-abdomen ( Fig. 3 D). The sperm duct remains bright red in formalin. No larvae have been found.

This species differs from other Aplidium having a dozen of stigmata rows and numerous stomach folds by the peculiar structure of the atrial siphon.

Figures

FIGURE 3. Aplidium boucheti n. sp.: A, thorax; B, branchial sac; C, abdomen; D, zooid; E, gut loop; F, atrial siphon. Scale bars: D = 2 mm; E = 0.5 mm.

FIGURE 4. A, Aplidium boucheti n. sp.: colony in formalin. B, Aplidium hestia n. sp.: colony in formalin. Scale bars: A, B = 1 cm.