Dictyosphaerium has traditionally been classified in its own family, Dictyosphaeriaceae,[4] or as part of the family Botryococcaceae, characterized by cells connected by gelatinous stalks or strands of mucilage.[5] However, molecular phylogenetic studies have demonstrated that Dictyosphaerium is closely related to the unicellular genus Chlorella, and is now currently placed in the family Chlorellaceae.[1]
Additionally, the morphotype of Dictyosphaerium (consisting of branching strands of mucilage connecting cells) is known to be polyphyletic, having evolved multiple times. Therefore, this morphotype can now be found in many new genera. For example, the genus Mucidosphaerium differs from Dictyosphaerium sensu stricto in having spherical cells, as opposed to Dictyosphaerium with oval cells.[6] The genus Mychonastes (including the former genus Pseudodictyosphaerium) differs in having chloroplasts without pyrenoids, and more irregular mucilaginous strands.[7]
Other similar genera include Compactochlorella, Kalenjinia, Marasphaerium, Masaia,[2] Hindakia, Heynigia,[8] and Xerochlorella.[9] These genera appear to be more or less cryptic, being reliably differentiated only by DNA barcoding.[10] Their biogeographical patterns remain unclear.[11]
