Phylogenetic study on Scenedesmacae with the description of a new genus Coccoidesmus gen. nov. (Chlorophyceae, Chlorophyta) and chloroplast genome analyses

Members of the family Scenedesmaceae are some of the most common algal taxa in inland ecosystems, and they are widely distributed in freshwaters, aerial, and sub-aerial habitats. With the continuous updating of methods, the classic morphological taxonomy of this family needs to be revised. In recent years, many genera of Scenedesmaceae have been established via the use of molecular methods. The phylogenetic relationships within Scenedesmaceae were analyzed using different molecular markers and morphological data, and the new freshwater genus Coccoidesmus Wang, Hou et Liu gen. nov. was described. Two new species in this genus were also described. Phylogenetic analysis based on tufA genes revealed that the new genus formed an independent clade closely related to Comasiella. However, these two genera are characterized by significant morphological differences in colony arrangement and cell shape. The chloroplast genome of the type species was assembled and annotated, and analyses of genome structure and sequences were conducted. More genome data could help clarify the phylogenetic relationships within this family.