[Correlation between the presence of a bacterial symbiont in oocytes of Parcellio dilatatus petiti, and the sterility of the cross: P.d. petiti male x P.d. dilatatus female].

A symbiotic bacteroid matroclinously transmitted is present in the ovocytes and the follicular cells of the sub-species Porcellio dilatatus petiti of the Saint-Honorat island, as well as in all hybrid females born from a petiti mother. It is absent in the Porfellio dilatatus dilatatus females (population of Poitiers) and this seems to cause the lithality in the periblastula stage -- as a result of abnormal anaphases--of practically all the embryos of the crossing : male petiti x female dilatatus.