''Spirotaenia'' is a genus of basal green algae that may be sister to the

Chlorokybophyceae ''Chlorokybus'' is a multicellular (sarcinoid) genus of basal green algae or Charophyta, charophyte, a soil algae, alga. It has been classified as the sole member of the family Chlorokybaceae, which is the sole member of the order Chlorokybales, ...

. It was previously considered to be part of the

Zygnemataceae The Zygnemataceae are a family of filamentous or unicellular, uniseriate (unbranched) green algae. The filaments are septated and reproduction is by conjugation; ''Spirogyra'' is commonly used in schools to demonstrate this kind of reproductio ...

. It is sexually conjugating, a mode of reproduction that was previously only known in the

Mesotaeniaceae The Mesotaeniaceae are a small family of unicellular green algae known as the "saccoderm desmids". The Mesotaeniaceae appear to be sister or ancestral to the Zygnemataceae. The desmids are a deep branching group of Zygnemataceae. ''Spirotaeni ...

, the sister groups to the

land plants The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as sist ...

. This is surprising, as ''Spirotaenia'' is much more basal. The conjugating process is substantially aberrant. ''Spirotaenia'' may actually be more than one distinct lineage which may not be closely related.

Phylogeny

References

Green algae {{Alga-stub