[The forms of the population variability of the chitinoid formations in Tetraonchus monenteron (Monogenea: Tetraonchidae)].

Population variability of the adhesive apparatus and copulatory organ of Tetraonchus momenteron from young and adult pikes (Esox lucius) from Rybinsk reservoir (Volga river system) and adult pikes from lake Baikal has been studied. Comparison analysis of seven plastic and one meristic characters allowed to discover differences between the groups of monogeneans from young and adult pikes from "rybinsk" population by frequently of the variations of number of the tight coils of copulatory organ support bar. Differences between "rybinsk" and "baikal" populations of T. monenteron were found. The "baikal" monogeneans differ from the "rybinsk" ones by frequently of the copulatory organ phenes and also more large sizes of the chitinoid formations.