Class Trebouxiophyceae The class Trebouxiophyceae was described based on the genetic similarity of investigated strains as a group of algae with non-flagellated vegetative cells, unicellular, sarcinoid, or filamentous thalli (Friedl 1995). Phylogenetically the Trebouxiophyceae is the sister group to the Chlorophyceae and Ulvophyceae, and can be further subdivided into six main lineages: Trebouxiales, Watanabeales, Elliptochloris -clade, Prasiolales, Chlorellales and Microthamniales (Leliaert et al. 2012; Lemieux et al. 2014; Darienko et al. 2016; Li et al. 2021). Members of most of these lineages (except for the order Microthamniales) have been found to associate with lichens (e.g. Thüs et al. 2011; Škaloud et al. 2015). The nature of the relationships between these lineages remains unclear, and some studies even question the monophyly of the entire class (Leliaert et al. 2012).

Published as part of Veselá, Veronika, Malavasi, Veronica & Škaloud, Pavel, 2024, A synopsis of green-algal lichen symbionts with an emphasis on their free-living lifestyle, pp. 317-338 in Phycologia 63 (3) on page 318, DOI: 10.1080/00318884.2024.2325329, http://zenodo.org/record/15520507