Craticula vanensis sp. nov., a new species of diatom with a complex mitogenome, inhabiting soda lakes in central Europe and Anatolia

This article formally describes Craticula vanensis sp. nov., a new species of diatom from Lake Van, the largest soda lake in the world, and the fifth new species identified in the lake following an 81-years gap in investigations. A genomic approach based on short reads allowed the complete cluster of nuclear rRNA genes to be retrieved alongside the complete plastome, both later used in several single or multigene phylogenies, which surprisingly tended to associate C. vanensis to species of the genus Dorofeyukea. The complex structure of the mitogenome could only be resolved by long-read sequencing. It is characterized by its large size (116,698 bp), the presence of several introns in the cox1 gene, the use of an alternative genetic code with the putative reassignment of the UGA codon to arginine and the unexpected presence of six copies of the rRNA genes and nine copies of truncated nad2 sequences. A survey of published metabarcoding datasets suggested the presence of C. vanensis in a soda lake from Central Europe (Kakasszéki, Hungary), which was later confirmed by microscopy and suggests an extended distribution of this taxon.