Atopkin D.M., Ivashko Ya.I., Besprozvannykh V.V., Frolov E., Urabe M., Voropaeva E., Sokolov S.G.
В журнале Systematics and Biodiversity
Год: 2025 Номер: 23 Выпуск: 1 ArticleID: 2560310
The genus Azygia Looss, 1899 comprises plagiorchiid digeneans of freshwater fishes distributed in the northern hemisphere. Its taxonomic boundaries are contestable, and identification of some reported material is uncertain. We performed a phylogenetic analysis of Palaearctic representatives of Azygia based on five molecular markers and described a new species of this genus from Amur pike Esox reichertii Dybowski, 1869 from the Russian Far East. We found that Azygia was diverged into three phylogenetic lineages with unclear relationships. Lineage 1 and Lineage 2 were represented by Palaearctic species of Azygia, while Lineage 3 comprised Nearctic azygiids, particularly Nearctic species of Azygia and representatives of the genera Leuceruthrus Marshall & Gilbert, 1905 or Proterometra Horsfall, 1934. The new species, Azygia shedkoae sp. nov., belonged to Lineage 2 together with Azygia lucii (M€uller, 1776), Azygia robusta Odhner, 1911, and Azygia sibirica Vainutis, Voronova & Zhokhov, 2023. Morphologically, the new species is close to A. robusta but differs from it in the length of the forebody, the length of post-testicular space, and the length of uterine fields as well as genetically. Our data demonstrate a deep molecular differentiation of the azygiid lineages apparently resulting from some complex long-term evolutionary processes. We found no arguments in favour of the recently proposed synonymization of Azygia and Leuceruthrus. At the same time, our results appear to indicate that Azygia should be divided into several distinct genera.
