Intersection of Chlorella, Muriella and Bracteacoccus: Resurrecting the genus Chromochloris Kol et Chodat (Chlorophyceae, Chlorophyta).

Abstract

Coccoid green algae generally are difficult to classify because of their depauperate morphology, and for this reason many of them have a complicated taxonomic history. In the present study we use analyses of molecular sequence data to demonstrate the close relationship of two green coccoid taxa that have undergone multiple taxonomic transfers in the past, and argue for the recognition of a distinct lineage. We resurrect the genus Chromochloris to accommodate C. zofingiensis (= Muriella zofingiensis) and we provide data regarding the lineage's phylogenetic relationships to other chlorophyte genera, especially Bracteacoccus, Chlorella, Muriella, Mychonastes, and Pseudomuriella. In addition, we synonymize B. cinnabarinus and Bracteacoccus minutus with C. zofingiensis, and clarify the identity of three UTEX strains heretofore listed as Bracteacoccus.