[Hypothesis of the biogeographical origin of Diplozoon (Monogenea, Polyopisthocotylea)].

The evolutionary geographic origin of Diplozoon and Octomacrum (Monogenea, Polyopisthocotylea) is discussed. Diplozoon occurs in Eurasia and Africa, whereas the distribution of Octomacrum is limited to North-America. These two monogeneans likely had a common progenitor originating from the Pacific. This hypothesis is suggested by the morpho-anatomical resemblances between Diplozoon and Octomacrum and by the analysis of their geographic distribution.