Chlorellaceae

Members of Chlorellaceae are morphologically diverse and include solitary and colonial forms. Traditionally, the family was circumscribed based on the mode of reproduction (production of autospores), and the family was defined around the type genus Chlorella, which is generally solitary and consists of spherical cells. However, based on molecular evidence, a number of genera have been moved into Chlorellaceae that differ significantly in morphology; these include Actinastrum (elongate cells in colonies), Micractinium (spherical cells with bristles), and Didymogenes (colonial cells with a thick mucilaginous envelope). Cells generally contain a single chloroplast with a pyrenoid. In addition to autotrophic members that contain a chloroplast, the family includes genera which have lost the ability to photosynthesize are therefore heterotrophic. These genera, namely Prototheca and Helicosporidium, are colorless, single-celled organisms that resemble yeast, and are opportunistic pathogens of animals. ==Genera==

As of 2025, AlgaeBase includes the following genera: • Acanthosphaera • Actinastrum • Apodococcus • Auxenochlorella • Ava • Brachionococcus • Carolibrandtia • †Caryosphaeroides • Catena • Chlorella • Chloroparva • Closteriopsis • Compactochlorella • Coronacoccus • Coronastrum • Cylindrocelis • Dicellula • Dicloster • Dictyosphaerium • Didymogenes • Endolithella • Geminella • Gloeotila • Golenkiniopsis • Hegewaldia • Helicosporidium • Heynigia • Hindakia • Hormospora • Kalenjinia • Keratococcus • Laetitia • Lewiniosphaera • Marasphaerium • Marinichlorella • Marvania • Masaia • Meyerella • Micractinium • Mucidosphaerium • Muriella • Nannochloris • Nanochlorum • Nomia • Palmellochaete • Parachlorella • Planktochlorella • Podohedra • Prototheca • Pseudochloris • Pseudosiderocelopsis • Pumiliosphaera • Siderocelis ==Phylogeny==

Higher-order relationships within Chlorellaceae are largely unresolved, with conflicting topologies; however, there are several well-supported clades: • The Chlorella clade, containing Chlorella as well as other genera such as Actinastrum and Micractinium: • The Parachlorella clade, containing Parachlorella and other genera such as Dictyosphaerium: }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} Not all genera are included, as some (e.g. Cylindrocelis, Palmellochaete, etc.) have not been studied using molecular methods. In addition, some genera such as Geminella appear to cluster outside of Chlorellales. ==References==