Eudistoma illotum

Etymology. In Latin pustulosus = with pustules Station. TA 56 (MNHN A 3 EUD 353 Holotype) The single colony is a sheet 7 x 5.5 cm large and 0.8 mm thick, completely embedded with sand. The surface is erected in small round protrusions as pimples (Fig. 22 E), each of them containing the siphons of one zooid. The tunic is glassy, colourless and resistant. The zooids (Fig. 22 F) occupy the whole thickness of the colony, perpendicular to the surface. The siphons are short with 6 lobes. The body wall is opaque and colourless. The thorax, always contracted, counts about 25 stigmata on each side in the median row. The abdomen narrow at its beginning is enlarged at the gonad level. The stomach is short, smooth walled, at 2 / 3 of the abdomen length. The intestinal loop is straight without individualised compartments. The gonads occupy a large part of the gut loop behind the stomach with very numerous testis vesicles in a bush and a central ovary. Small irregular shining crystals are scattered upon the gonad mass. Post-abdominal vascular processes are present. Two or three embryos are incubated in the atrial cavity distended even in less contracted zooids but which does not form a pedunculate pouch. The mature larva is 0.8 mm long, colourless, with a tail in ¾ of a turn. The 3 adhesive papillae are divergent, sided by 4 large vesicles; the median ones are bi-dentate on each side or only one of them is bi-dentate on a side (Fig. 22 G, H). Among the sandy Eudistoma species of the Indian Ocean, this new species differs by the shape of the colony with both siphons of each zooid grouped in a surface protrusion of the tunic.