Extending the knowledge of taxonomy, biodiversity, and biogeography of Arctic ichthyofauna: A case study of the most diverse genus Lycodes (Zoarcidae)

Eelpout genus Lycodes (Zoarcidae) is the most species-rich genus of fishes in the Arctic seas. The species composition and the actual ranges of some Arctic eelpouts are still questionable due to insufficient research efforts and often incorrect species identifications. A new material on 12 species of eelpout genus Lycodes was collected during 2019 research cruise in four seas of Siberian Arctic (western Chukchi, East Siberian, Laptev, and Kara seas). The morphological characters, variability and distribution of these species are described and discussed. Four species are discovered in new areas, i.e. Lycodes reticulatus were for the first time reported for the East Siberian Sea, Lycodes pallidus for the Chukchi Sea, Lycodes raridens for the Laptev Sea, and Lycodes rossi in the Chukchi and East Siberian seas. These records significantly extend our knowledge on the modern ranges of these species, and may testify to the expansion of Pacific species into the Arctic. Results obtained show that L. pallidus and Lycodes polaris might be the most abundant and widespread species occurred in three Siberian Arctic seas, while former species is characterized by the widest range of morphological variability. A data presented contribute to monitoring of the biodiversity of Arctic ecosystems that are transforming rapidly in the face of climate change and increasing anthropogenic pressure.