''Mesostigma'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of freshwater

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

, with a single species ''Mesostigma viride''. , AlgaeBase classified it as the only genus in the family Mesostigmataceae, the only family in the order Mesostigmatales, the only order in the class Mesostigmatophyceae. It is now considered to be one of the earliest diverging members of green plants/algae ( Viridiplantae). Earlier studies were unable to resolve the position of the species, and it was often placed as a sister to all other green algae, as one of the basal members of the Streptophyta, or as close to ''

Chaetosphaeridium ''Chaetosphaeridium'' is a genus of green algae. Several classifications have been proposed. Its traditional classification is in the order Coleochaetales, related to the genus ''Coleochaete''. AlgaeBase places it in the order Chaetosphaeridiales ...

''. More recent studies agree that ''Mesostigma'' and ''

Chlorokybus ''Chlorokybus'' is a multicellular (sarcinoid) genus of basal green algae or charophyte, a soil alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grou ...

'' form a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

, being the earliest diverging

green plants Viridiplantae (literally "green plants") are a clade of eukaryotic organisms that comprise approximately 450,000–500,000 species and play important roles in both terrestrial and aquatic ecosystems. They are made up of the green algae, which ar ...

References

External links

from Algaebase Charophyta genera Monotypic algae genera {{Algae-stub