The first finding of the Black Sea snail Lithoglyphus naticoides (Gastropoda) and its associated species-specific trematoda in the Upper Volga basin

After the first finding in the Volga River delta in early 1990s, the Ponto-Azov snail Lithoglyphus naticoides expanded its range toward the northern water bodies of the Upper Volga basin. During 2004–2007, new populations of L. naticoides with a high level of infection by specific trematode species were found in the Cheboksary and Rybinsk reservoirs. In addition, metacercariae of the genus Apophallus associated with L. naticoides were noted in the fishes of the Gorky and Ivankov reservoirs.