Ultrastructure of the male gamete of Brachylecithum eliomydis (Digenea, Dicrocoeliidae)—A parasite of Eliomys quercinus (Rodentia, Gliridae)

The male gametes of Brachylecithum eliomydis (Digenea, Dicrocoeliidae) a parasite of Eliomys quercinus “the garden dormouse” caught in France were described by micrographs of transmission electron microscopy (TEM). The mature spermatozoon of B. eliomydis presents classical characteristics early described in digenean species such as the two axonemes of different lengths with the 9+“1” pattern of the trepaxonematan platyhelminthes, two bundles of parallel cortical microtubules, two mitochondria, a nucleus and granules of glycogen. Moreover, several characteristics, described in the spermatozoon of B. eliomydis, vary within digenean taxa. Those are (1) the morphology of anterior and posterior spermatozoon extremities, (2) the external ornamentation of the plasma membrane and its association or not with cortical microtubules, (3) the presence or absence of spine-like bodies and (4) the number of cortical microtubules and their organization into one or two parallel bundles. Using these four criteria, the morphology of the mature spermatozoon of B. eliomydis was compared to that of the other dicrocoellids, brachycoeliids, paragonimids and troglotrematids species described so far. The general morphology of the spermatozoon described in B. eliomydis, could characterize the family Dicrocoeliidae.