Mesostigma

{{Short description|Genus of algae}}

{{Automatic taxobox

| image =

| image_caption =

| taxon = Mesostigma

| authority = Lauterborn

| parent_authority = Marin & Melkonian

| grandparent_authority = Marin & Melkonian

| subdivision_ranks = Species

| subdivision =

• M. viride Lauterborn

}}

Mesostigma is a genus of unicellular biflagellate freshwater green algae, with a single species Mesostigma viride, covered by an outer layer of basket‐like scales instead of a cell wall.{{Cite journal |last1=Liang |first1=Zhe |last2=Geng |first2=Yuke |last3=Ji |first3=Changmian |last4=Du |first4=Hai |last5=Wong |first5=Chui Eng |last6=Zhang |first6=Qian |last7=Zhang |first7=Ye |last8=Zhang |first8=Pingxian |last9=Riaz |first9=Adeel |last10=Chachar |first10=Sadaruddin |last11=Ding |first11=Yike |last12=Wen |first12=Jing |last13=Wu |first13=Yunwen |last14=Wang |first14=Mingcheng |last15=Zheng |first15=Hongkun |date=2020 |title=Mesostigma viride Genome and Transcriptome Provide Insights into the Origin and Evolution of Streptophyta |journal=Advanced Science |volume=7 |issue=1 |pages=1901850 |doi=10.1002/advs.201901850 |pmc=6947507 |pmid=31921561}}{{AlgaeBase taxon|name=Mesostigma|id=113394}} It is the only known genus in the class Mesostigmatophyceae{{AlgaeBase taxon|name=Mesostigmatophyceae|id=113391}} (and thus, the only genus in the family Mesostigmataceae{{AlgaeBase taxon|name=Mesostigmataceae|id=113393}} and the order Mesostigmatales{{AlgaeBase taxon|name=Mesostigmatales|id=113392}}).

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.{{cite journal | doi = 10.1016/S1434-4610(99)70041-6 | vauthors = Marin B, Melkonian M | author2-link = Michael Melkonian | year = 1999 | title = Mesostigmatophyceae, a new class of streptophyte green algae revealed by SSU rRNA sequence comparisons | journal = Protist | volume = 150 | pages = 399–417 | pmid = 10714774 | issue = 4 }}{{cite journal | title = The plant tree of life: an overview and some points of view | author = Jeffrey D. Palmer | author2 = Douglas E. Soltis | author3 = Mark W. Chase | name-list-style = amp | journal = American Journal of Botany | year = 2004 | volume = 91 | pages = 1437–45 | doi = 10.3732/ajb.91.10.1437 | issue=10 | pmid=21652302| doi-access = free }}{{cite journal | title = EST analysis of the scaly green flagellate Mesostigma viride (Streptophyta): Implications for the evolution of green plants (Viridiplantae) | author = Andreas Simon | author2 = Gernot Glöckner | author3 = Marius Felder | author4 = Michael Melkonian | author4-link = Michael Melkonian | author5 = Burkhard Becker | name-list-style = amp| journal = BMC Plant Biology | year = 2006 | volume = 6 | pages = 2 | doi = 10.1186/1471-2229-6-2 | pmid = 16476162 | pmc = 1413533 | doi-access = free }} More recent studies agree that Mesostigma and Chlorokybus form a clade, being the earliest diverging of the green plants, specifically within Charophytes.{{cite journal |vauthors=Lemieux C, Otis C, Turmel M |title=A clade uniting the green algae Mesostigma viride and Chlorokybus atmophyticus represents the deepest branch of the Streptophyta in chloroplast genome-based phylogenies |journal=BMC Biol. |volume=5|pages=2 |year=2007 |pmid=17222354 |pmc=1781420 |doi=10.1186/1741-7007-5-2 |doi-access=free }}{{Cite journal |last1=Becker |first1=B. |last2=Marin |first2=B. |year=2009 |title=Streptophyte algae and the origin of embryophytes |journal=Annals of Botany |volume=103 |issue=7 |pages=999–1004 |doi=10.1093/aob/mcp044 |name-list-style=amp |pmid=19273476 |pmc=2707909 }}{{Cite journal|last1=Sánchez-Baracaldo|first1=Patricia|last2=Raven|first2=John A.|last3=Pisani|first3=Davide|last4=Knoll|first4=Andrew H.|date=2017-09-12|title=Early photosynthetic eukaryotes inhabited low-salinity habitats|journal=Proceedings of the National Academy of Sciences|volume=114|issue=37|pages=E7737–E7745|doi=10.1073/pnas.1620089114|pmid=28808007|pmc=5603991|bibcode=2017PNAS..114E7737S |doi-access=free}}{{Cite journal|last1=Gitzendanner|first1=Matthew A.|last2=Soltis|first2=Pamela S.|last3=Wong|first3=Gane K.-S.|last4=Ruhfel|first4=Brad R.|last5=Soltis|first5=Douglas E.|date=2018|title=Plastid phylogenomic analysis of green plants: A billion years of evolutionary history|journal=American Journal of Botany|language=en|volume=105|issue=3|pages=291–301|doi=10.1002/ajb2.1048|pmid=29603143|issn=0002-9122|doi-access=free}}