Mychonastes frigidus sp. nov. (Sphaeropleales/Chlorophyceae), a new species described from a mountain stream in the Subpolar Urals (Russia)

This paper describes a new species from the Class Chlorophyceae, Mychonastes frigidus sp. nov., isolated from a cold-water mountain stream in the north of Russia (Subpolar Ural). The taxon is described using morphological and molecular methods. Mychonastes frigidus sp. nov. belongs to the group of species of the genus Mychonastes with spherical single cells. Comparison of ITS2 rDNA sequences and its secondary structures combined with the compensatory base changes approach confirms the separation between Mychonastes frigidus sp. nov and other species of the genus. Mychonastes frigidus sp. nov. represents a cryptic species that can only be reliably identified using molecular data.