On the New Record of Vaucheria vipera (Vaucheriaceae, Xanthophyceae), with Remarks on its Sectional Placement

The report provides new data on Vaucheria vipera Blum, one of the rarest collected marine species. In 2023, V. vipera was discovered in the littoral zone of the Unskaya Inlet of the White Sea. The record is considered first in Russia and the Arctic Ocean. The study of the morphology of specimens from the White Sea allowed to expand the morphological range of the species in terms of the maximum dimensions of oogonia, oospores, and antheridia. The work also pays attention to the basal septa that separate short branches bearing the gametangia. Based on the morphology of the gametangia, it is proposed to transfer this species to the section Woroninia.