Myxobolus species (Cnidaria: Myxozoa) infecting roach Rutilus rutilus in Lake Baikal: morphological, molecular characteristics and spatial distribution

Myxobolus species are represented by a wide variety of species, especially in cyprinids, while their fauna in Palearctic fish is still poorly studied. In 2017-2018, we examined 200 specimens of roaches aged 0+ to 8+ in the Chivyrkuisky Bay of Lake Baikal, and identified four species of the genus Myxobolus (Myxozoa; Myxosporea): Myxobolus diversicapsularis, M. feisti, M. pseudodispar, M. zaikae. The article studies the features of seasonal and age-related dynamics of fish infestation and parasite-host relationships. M. diversicapsularis causes the most serious histopathological changes in summer. Hyperinvasion is accompanied by degeneration of blood vessels in the branchial lobes of the second order. The 18S rDNA sequences of the studied isolates have 100-99.3% identity with the species described in the Danube River basin (Hungary) from the Genbank database.