Chloroidium Nadson .

All eleven currently accepted Chloroidium species (Guiry & Guiry 2022) are characterized by an ellipsoidal, ovoid, or spherical cell shape bounded by a relatively thin cell wall that becomes thicker with age, a parietal lobed or lobe-less chloroplast (Fig. 5), and reproduction by unequally sized autospores. Representatives of this genus differ from the other Chlorella -like species in the production of ribitol, a metabolite typically produced in response to osmotic stress (Darienko et al. 2010). Chloroidium accommodates species, which were previously attributed to the various Chlorella species, including C. saccharophila, C. ellipsoidea, C. angusto-ellipsoidea, and C. viscosum, and later moved to the genus Chloroidium based on phylogenetic analyses (Darienko et al. 2010; Darienko et al. 2018). Chloroidium is a widely distributed genus that inhabits a variety of environments, including water (Darienko et al. 2018). Chloroidium ellipsoideum, C. saccharophilum, C. lichinum and C. viscosum were described as lichen symbionts (Thüs et al. 2011; Vančurová 2012; Darienko et al. 2018).