Editing Cyanobacteria (section)

=== Taxonomy ===
{{See also|Bacterial taxonomy}}
[[File:Haeckel arbol bn.png|thumb|upright|Tree of Life in ''Generelle Morphologie der Organismen'' (1866). Note the location of the genus
''[[Nostoc]]'' with algae and not with bacteria (kingdom "Monera")]]
Historically, bacteria were first classified as plants constituting the class Schizomycetes, which along with the Schizophyceae (blue-green algae/Cyanobacteria) formed the phylum Schizophyta,<ref name=nageli>{{cite journal |vauthors=Von Nägeli C |veditors=Caspary R |year=1857 |title=Bericht über die Verhandlungen der 33. Versammlung deutscher Naturforscher und Ärzte, gehalten in Bonn von 18 bis 24 September 1857 |trans-title=Report on the Proceedings of the 33rd Meeting of German Natural Scientists and Physicians, held in Bonn, 18 to 24 September 1857 |journal=[[Botanische Zeitung]] |volume=15 |pages=749–776}}</ref> then in the phylum [[Monera]] in the kingdom [[Protista]] by [[Haeckel]] in 1866, comprising ''Protogens, Protamaeba, Vampyrella, Protomonae'', and ''Vibrio'', but not ''Nostoc'' and other cyanobacteria, which were classified with algae,<ref>{{cite book | vauthors = Haeckel E |year=1867 |title=Generelle Morphologie der Organismen |url=https://archive.org/details/bub_gb_-5k5AAAAcAAJ |publisher=Reimer, Berlin}}</ref> later reclassified as the ''[[Prokaryotes]]'' by [[Édouard Chatton|Chatton]].<ref>{{cite journal |vauthors=Chatton É |title=''Pansporella perplexa'': amœbien à spores protégées parasite des daphnies réflexions sur la biologie et la phylogénie des protozoaires |trans-title=''Pansporella perplexa'': amoebian with protected spores parasite of daphnia reflections on the biology and phylogeny of protozoa |journal=Annales des sciences naturelles: Zoologie |series=10 |volume=VII |pages=1–84 |year=1925 |language=fr |url=https://gallica.bnf.fr/ark:/12148/bpt6k55415433 }}</ref>

The cyanobacteria were traditionally classified by morphology into five sections, referred to by the numerals I–V. The first three – [[Chroococcales]], [[Pleurocapsales]], and [[Oscillatoriales]] – are not supported by phylogenetic studies. The latter two – [[Nostocales]] and [[Stigonematales]] – are monophyletic as a unit, and make up the heterocystous cyanobacteria.<ref name="Gugger_2004">{{cite journal | vauthors = Gugger MF, Hoffmann L | title = Polyphyly of true branching cyanobacteria (Stigonematales) | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 54 | issue = Pt 2 | pages = 349–357 | date = March 2004 | pmid = 15023942 | doi = 10.1099/ijs.0.02744-0 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Howard-Azzeh M, Shamseer L, Schellhorn HE, Gupta RS | title = Phylogenetic analysis and molecular signatures defining a monophyletic clade of heterocystous cyanobacteria and identifying its closest relatives | journal = Photosynthesis Research | volume = 122 | issue = 2 | pages = 171–185 | date = November 2014 | pmid = 24917519 | doi = 10.1007/s11120-014-0020-x | bibcode = 2014PhoRe.122..171H }}</ref>

The members of Chroococales are unicellular and usually aggregate in colonies. The classic taxonomic criterion has been the cell morphology and the plane of cell division. In Pleurocapsales, the cells have the ability to form internal spores (baeocytes). The rest of the sections include filamentous species. In Oscillatoriales, the cells are uniseriately arranged and do not form specialized cells (akinetes and heterocysts).<ref>{{cite journal |url=http://www.preslia.cz/P144Komarek.pdf |title=Taxonomic classification of cyanoprokaryotes (cyanobacterial genera) 2014, using a polyphasic approach |vauthors=Komárek J, Kaštovský J, Mareš J, Johansen JR |journal=[[Preslia]] |volume=86 |pages=295–335 |year=2014}}</ref> In Nostocales and Stigonematales, the cells have the ability to develop heterocysts in certain conditions. Stigonematales, unlike Nostocales, include species with truly branched trichomes.<ref name="Gugger_2004" />

Most taxa included in the phylum or division Cyanobacteria have not yet been validly published under ''The International Code of Nomenclature of Prokaryotes'' (ICNP) <ref>https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijsem.0.005585a{{dead link|date=February 2025}}{{full|date=February 2025}}</ref> and are instead validly published under the [[International Code of Nomenclature for algae, fungi, and plants]]. These exceptions are validly published under ICNP:
* The families [[Prochloraceae]] and [[Prochlorotrichaceae]]
* The genera ''[[Halospirulina]], [[Planktothricoides]], [[Prochlorococcus]], [[Prochloron]]'', and ''[[Prochlorothrix]]''

Formerly, some bacteria, like ''[[Beggiatoa]]'', were thought to be colorless Cyanobacteria.<ref name="Pringsheim1963">{{cite book | vauthors = Pringsheim EG |title=Farblose Algen: Ein Beitrag zur Evolutionsforschung | trans-title = Colorless Algae: A Contribution to Evolutionary Research | language = de |url={{google books |plainurl=y |id=RYnPAAAAMAAJ}} |year=1963 |publisher=Gustav Fischer Verlag}}</ref>

The currently accepted taxonomy as of 2025 is based on the [[List of Prokaryotic names with Standing in Nomenclature]] (LPSN)<ref>{{cite web | vauthors = Euzéby JP |url=https://lpsn.dsmz.de/phylum/cyanobacteria |title="Cyanobacteria" |access-date=2022-01-22 |publisher=[[List of Prokaryotic names with Standing in Nomenclature]] (LPSN)}}</ref> and [[National Center for Biotechnology Information]] (NCBI).<ref>{{cite web |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=1117&lvl=3&lin=f&keep=1&srchmode=1&unlock |title=Cyanobacteria |access-date=2021-03-20 |publisher=[[National Center for Biotechnology Information]] (NCBI) taxonomy database |display-authors=etal}}</ref>
* Class [[Cyanophyceae]]
** Order Acaryochloridales <small>Miyashita et al. 2003 ex Strunecký & Mareš 2022</small>
*** Family Thermosynechococcaceae
** Order Aegeococcales <small>Strunecký & Mareš 2022</small>
** Order [[Chroococcales]] (synonyms [[Pleurocapsales]], Cyanobacteriales)
** Order [[Chroococcidiopsidales]]
** Order Coleofasciculales
** Order Desertifilales
** Order Geitlerinematales <small>Strunecký & Mareš 2022</small>
** Order [[Gloeobacterales]]
** Order Gloeomargaritales <small>Moreira et al. 2016</small>
** Order Gomontiellales
** Order Graniferales
** Order Leptolyngbyales (synonym Phormidesmiales) <small>Strunecký & Mareš 2022</small>
** Order Nodosilineales <small>Strunecký & Mareš 2022</small>
** Order [[Nostocales]] (synonym Stigonematales)
** Order Oculatellales (synonym Elainellales) <small>Strunecký & Mareš 2022</small>
** Order [[Oscillatoriales]]
** Order Pelonematales
** Order Prochlorotrichales <small>Strunecký & Mareš 2022</small> (PCC-9006)
*** Family Prochlorococcaceae <small>Komárek & Strunecky 2020</small> {"PCC-6307"}
** Order Sarmaellales
** Order [[Spirulinales]]
** Order [[Synechococcales]] (synonym Pseudanabaenales) <small>Hoffmann, Komárek & Kastovsky 2005</small>
** Order Thermostichales <small>Komárek & Strunecký 2020</small>
* Class [[Vampirovibrionophyceae]]
** Order [[Vampirovibrionales]]