''Mesostigma'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of unicellular biflagellate freshwater
green algae
The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...
, with a single species ''Mesostigma viride'', covered by an outer layer of basket‐like scales instead of a
cell wall
A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...
.
It is the only known genus in the class
Mesostigmatophyceae (and thus, the only genus in the family Mesostigmataceae
and the order Mesostigmatales
).
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, close to ''
Chaetosphaeridium''. More recent studies agree that ''Mesostigma'' and ''
Chlorokybus'' form a
clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
, being the earliest diverging of the
green plants, specifically within
Charophytes
Charophyta () is a Paraphyly, paraphyletic group of freshwater green algae, called charophytes (), sometimes treated as a Division (taxonomy), division, yet also as a Division (taxonomy), superdivision. The terrestrial plants, the Embryophyta em ...
.
References
External links
from Algaebase
Charophyta genera
Monotypic algae genera
{{green algae-stub