Chloromonas; cryptic diversity; ecology; freshwater; polyphasic approach; terrestrial

The phylogroup Chloromonadinia (Volvocales, Chlorophyceae) encompasses ecologically versatile green microalgae with a predominantly freshwater and snow lifestyle. Although a few species have been described from soils, the evolutionary history of terrestrial volvocalean flagellates is poorly known due to undersampling. Here we provide new insights into the phylogenetic position of terrestrial flagellates within the Chloromonadinia and investigate six unresolved strains from terrestrial and freshwater habitats in both hemispheres. The terrestrial strains differed in cell morphology, ultrastructure and lifestyle from the freshwater ones, therefore, we expected them to represent distinct evolutionary lineages (species or genera).