The Species Diversity Assessment of Azygia Looss, 1899 (Digenea: Azygiidae) from the Volga, Ob, and Artyomovka Rivers Basins (Russia), with Description of A. sibirica n. sp.

This study is devoted to the investigation of Azygia (Digenea: Azygiidae) species diversity using classical morphological, recent molecular tools (28S rRNA and cox1 mtDNA for genetic-based inference) robust statistical techniques (Principal component analysis, PCA). The analysis revealed that genus included four valid species: A. lucii, longa, hwangtsiyui, sibirica n. sp. distribution type lucii was confirmed in largest Russian rivers: Volga Ob. worms isolated from Perccottus glenii were determined as Chinese according genetic data gene, at 1.32–1.56%. new species, sp, described Esox lucius Ob River differentiated by smaller ovary, testes prostatic sac, wider body, very narrow pharyngeal lumen form anterior margin ovary. In addition, multivariate three methods delimitation (ABGD, GMYC, bPTP) showed subdivision into two separate groups, one another River, respectively. To conclude, infects western (European part Russia, basin), northern (Western Siberia, basin) parts Russia; has also been found infect while hwangtsiyui South Far East (the Artymovka basin).