In collaboration with Jan de Vries, Sebastian Hess, and others, we have published a new classification of Zygnematophyceae. Genome-scale molecular phylogenetic analyses consistently show the zygnematophytes as the sister to embryophytes. This came as something of a surprise (at least to me) because of the structural simplicity of zygnematophytes when compared to their close relatives in the Coleochaetophyceae and Charophyceae (sensu stricto). In this context, understanding the phylogenetic branching order within the zygnematophytes becomes more important than ever, because we can only reliably reconstruct the properties of the ancestor when we have a good understanding of the relationships among the descendants.
Into context comes a transcriptomic dataset from Mougeotiopsis calospora PALLA. M. calospora was described in 1894, but it is rarely found and had previously not been analyzed with molecular data. Hess et al. obtained an Illumina (high-throughput, short-read) transcriptome from M. calospora, and used it for a phylogenetic analysis of 326 well-curated protein-coding genes from 83 other organisms representing zygnematophytes, embryophytes (land plants), and other streptophyte and chlorophyte green algae. This analysis placed M. calospora in a monophyletic group with Serritaenia sp. and “Mesotaenium endlicherianum”, and we propose a new ordinal name, Serritaeniales for this group.
Nomenclature isn’t always the most engaging aspect of the biological sciences, but the language that we use affects how we think about things, and having names that accurately reflect the best information on relationships currently available helps us think clearly about evolution. M. calospora is a fascinating organism, and I am pleased to have been able to help find its place on the tree of life.
Sebastian Hess, Shelby K Williams, Anna Busch, Iker Irisarri, Charles F Delwiche, Sophie de Vries, Tatyana Darienko, Andrew J Roger, John M Archibald, Henrik Buschmann, Klaus von Schwartzenberg, Jan de Vries 2022 A phylogenomically informed five-order system for the closest relatives of land plants Current Biology 32:4473-4482. https://doi.org/10.1016/j.cub.2022.08.022
