Eudistoma vannamei Millar, 1977

Monniot, Françoise, 2016, Ascidians (Tunicata) of the French Guiana Expedition, Zootaxa 4114 (3), pp. 201-245 : 213-214

Eudistoma vannamei Millar, 1977

Figure 9 .

Stations. SS1; SS3; SS4; SS5; SS10; SS11; SS12; SC7; SC13; SR4; SR7; SR8; SR10; SR11; SB3; SD8; SD9; SD15.

The colonies are composed of very soft clear elongated lobes erect on a wide encrusting base ( Fig. 9 A). The tunic is naked and slightly transparent in the upper part but not vitreous in formalin. Some thin mud adheres to the base of the colony. All characters are those described and figured by Millar (1977) and Oliveira et al (2014). E. vannamei is distinct from the other Eudistoma present in Guiana by its multiple soft naked lobes, a wide thorax ( Fig. 9 B) and the particularly large larva up to 1.6mm long superficially spotted by numerous small round vesicles ( Fig..9 C). As figured by Millar (1977 Fig. 10 D) the larva has a thick short ectodermic ampulla dorsal to the first adhesive papilla, 1 long ampulla between the first and second papillae, 2 long parallel ampullae between the second and third papillae and a ventral ectodermic thickening. The round brown superficial spots are located in a thin layer of tissue easily torn in removing the larva out of the atrial cavity.

Abundant along the shores of the Salut Islands E. vannamei is only recorded elsewhere from the northern Brazilian coast.

Clavelina brasiliensis ( Millar,1977)

= Podoclavella brasiliensis Millar, 1977

Station. SD15.

The solitary zooids are erect in long stiff vitreous tubes up to 8cm long wearing epibionts except at the top of the thoracic area. The oral siphon is oriented toward the ventral side and the atrial aperture opens somewhat posteriorly. Both have a smooth edge. The material is in poor condition and the oral tentacles in a circle could not be counted. The musculature forms strong but short ribbons, 2 dorsal and 6 transverse well apart from each other.

The branchial sac has 20 rows of stigmata. The rapheal languets are long and sharp issued from the transverse vessels in high blades. The abdomen is long and extends in a vascular process occupying the largest part of the tunic tube. The stomach is rectangular with a smooth wall located at some distance from the base of the gut loop. The anus with a smooth rim opens at the base of the thorax. The gonads lie on both sides of the gut loop behind the stomach with numerous testis lobes and a central ovary. Larvae 0.6mm in length with a tail in half circle lie in the atrial cavity.

This species described from 23°S from the Brasilian coast was recorded again from the Guyana shelf ( Millar 1978) at 53°W. The new material collected from Guiana in spite of its poor condition obviously corresponds to Millar’s species. The geographic distribution is presently restricted to the western tropical Atlantic.

Figures

FIGURE 9. Eudistoma vannamei. A, colony; B, stained thorax; C, larva not stained. Scale bars: B = 0.2 mm; C = 0.5 mm.

FIGURE 10. Stomozoa roseola. A, colony in formalin; B, branchial sac. Scale bar = 2.5 mm.