An algae-invertebrate symbiosis in Belle-Isle-en-Mer (France): the platyhelminthe Convoluta roscoffensis and the prasinophycean Tetraselmis convolutae

Convoluta roscoffensis is a symbiotic plathyhelminthe associated with the p rasinophycean alga Tetraselmis convolutae. This endosymbiosis, based upon a carbon exchange and a physical protection of the alga by the plathyhelmint he, is first described, as well as its inheritance. After this review on th e biology of the association, three new stations in South Brittany (Belle-I sle-en-Mer, Morbihan, France) are described. Their geographical position is intermediate between the previously described locations (South European At lantic coast and the Channel). They suggest a broader ecological range for this often ignored association and underline its extreme tolerance to physi cal disturbance. To conclude, the mutualisme of this invertebrate-alga asso ciation is discussed.