The reproductive cycle and the glochidium of Anodonta cygnea L. from Lago Trasimeno (Central Italy)

The different phases of the biological cycle of Anodonta cygnea L. living in lake Trasimeno (Central Italy) are described in the present paper. Researches have been carried out on histological sections of germinal tissues and gills of specimens of both sexes sacrificed every month and verified by following the course of the parasitic phase of life of glochidia on the fish of the lake. Moreover, the various species of fish heavily infested by glochidia have been identified and the glochidium infestation frequency has been determined. The structure of the glochidium shell has been studied with the scanning microscope for a better understanding of the mechanism of attachment to fish and to collect more information in order to compare the species of Anodonta from lake Trasimeno with those of other parts of Europe.