Les particularités biologiques et écologiques favorisant le recrutement de Gymnophallus nereicola J. Rebecq et G. Prévot, 1962 (Digenea, Gymnophallidae) par l’Annélide polychète Nereis diversicolor

Abstract

Metacercariae of Gymnophallidae are generally parasites of Molluscs. Only some species have metacercariae occurring in Annelid. Gymnophallus nereicola J. Rebecq et G. Prévot, 1962 is a mediterranean species. His life cycle is characterized by only one second intermediate host, Nereis diversicolor. In consideration of this atypical host, several peculiarities are necessary for the development of G. nereicola life cycle. These features are studied in this paper. Some have relation with the parasite: large number of cercariae; behaviour; swimming trajectory; cephalic glands. Some others have relation with the second intermediate host; cercarial attraction; metacercarial microhabitat. After all, others characters are ecological features: special parasite endemiotop, nearness of first and second intermediate hosts. All these particularities are in favour of a positive recruitment of Gymnophallus nereicola.