A New Species of Colorless Flagellates, <i>Thaumatomonas sibirica</i> sp. n. (Thaumatomonadida, Protista) According to Ultrastructural Data and Molecular Phylogeny

Thaumatomonads are common in soil and fresh water and play an important role in microbial communities. They use silicon for the intracellular synthesis of species-specific silica-scales that cover the surface of their cells. Their diversity is not well studied, and the combination of electron microscopy and molecular phylogeny of marker genes allowed the discovery of a new taxon. In this work, we established the Thaumatomonas strain IW08m from the Irkutsk Reservoir Bay (Eastern Siberia, Russia) into a monoculture and, using various microscopy methods, described its cell structure, including the stage of silica-scale formation. Based on combined data from the fine structure of the scales and phylogenetic analysis of the 18S rRNA gene, we showed congruence of morphological differences and genetic distances in the genus Thaumatomonas and described a new species, Thaumatomonas sibirica n. sp., and thus expanded our understanding of the diversity of thaumatomonads.