First record of metacercariae trematodes Opisthioglyphe ranae (Digenea: Telorchiidae) and Echinostoma bolschewense (Digenea: Echinostomatidae) in Dreissena polymorpha (Bivalvia: Dreissenidae) from the Don and Volga river basins, Russia

It is well known that an invasive bivalve mollusk species Dreissena polymorpha plays a significant role as a host to parasites. Currently, the interaction between digenean trematodes and their bivalve hosts remains relatively poorly understood. In this study we investigate infection of D. polymorpha by trematodes using molecular genetics, histological, and light microscopy methods. We obtained sequences of one mitochondrial (molecular cytochrome c oxidase subunit 1 (COI)) and two nuclear (ITS2, rDNA 28S) gene markers. To the best of our knowledge, this is the first time that infection of metacercariae of Opisthioglyphe ranae and Echinostoma bolschewense in D. polymorpha has been detected. Our sequence was 100% identical to the 28S rDNA of the species O. ranae recorded in Penza Oblast (Russia) in pond frog. At the same time, some sequences of the 28S rDNA of O. ranae detected in Penza Oblast (Russia) and Ivano-Frankovsk Region (Ukraine) were different from our sequence by 0.2%. Our sequence was 100% identical to the 28S rDNA of the species E. bolschewense sequenced in Slovakia. In addition, we received sequences of COI for both trematode species and ITS2 of E. bolschewense for the first time.