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{{For|an explanation of very similar terms|Excavata}}{{short description|Phylum of excavate protists}}
{{Short description|Phylum of excavate protists}}
{{For|an explanation of very similar terms|Excavata}}
{{Automatic taxobox
{{Automatic taxobox
| image = Giardia lamblia.jpg
| image = Giardia lamblia.jpg
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| authority = [[Grassé]] 1952 ''[[emend.]]'' [[Cavalier-Smith]] 2003
| authority = [[Grassé]] 1952 ''[[emend.]]'' [[Cavalier-Smith]] 2003
| display_parents = 2
| display_parents = 2
⚫
| synonyms = [[Archezoa]]?
⚫
| synonyms_ref = <ref name="Al Jewari Baldauf 2023"/>
| subdivision_ranks = Classes & orders
| subdivision_ranks = Classes & orders
| subdivision =
| subdivision = * [[Anaeramoeba]]<ref>{{Cite journal |last1=Stairs |first1=Courtney W. |last2=Táborský |first2=Petr |last3=Salomaki |first3=Eric D. |last4=Kolisko |first4=Martin |last5=Pánek |first5=Tomáš |last6=Eme |first6=Laura |last7=Hradilová |first7=Miluše |last8=Vlček |first8=Čestmír |last9=Jerlström-Hultqvist |first9=Jon |last10=Roger |first10=Andrew J. |last11=Čepička |first11=Ivan |date=2021-12-20 |title=Anaeramoebae are a divergent lineage of eukaryotes that shed light on the transition from anaerobic mitochondria to hydrogenosomes |journal=Current Biology |language=English |volume=31 |issue=24 |pages=5605–5612.e5 |doi=10.1016/j.cub.2021.10.010 |issn=0960-9822 |pmid=34710348|s2cid=240054026 |doi-access=free }}</ref>
* [[Anaeramoebidae]]<ref>{{Cite journal |last1=Stairs |first1=Courtney W. |last2=Táborský |first2=Petr |last3=Salomaki |first3=Eric D. |last4=Kolisko |first4=Martin |last5=Pánek |first5=Tomáš |last6=Eme |first6=Laura |last7=Hradilová |first7=Miluše |last8=Vlček |first8=Čestmír |last9=Jerlström-Hultqvist |first9=Jon |last10=Roger |first10=Andrew J. |last11=Čepička |first11=Ivan |date=2021-12-20 |title=Anaeramoebae are a divergent lineage of eukaryotes that shed light on the transition from anaerobic mitochondria to hydrogenosomes |journal=Current Biology |language=English |volume=31 |issue=24 |pages=5605–5612.e5 |doi=10.1016/j.cub.2021.10.010 |issn=0960-9822 |pmid=34710348|s2cid=240054026 |doi-access=free }}</ref>
* [[Parabasalid|Parabasalia]]
* [[Parabasalid|Parabasalia]]
** [[Trichonymphea]]
** [[Trichonymphea]]
Line 18: Line 18:
* [[Fornicata]]
* [[Fornicata]]
** [[Carpediemonas|Carpediemonadida]]
** [[Carpediemonas|Carpediemonadida]]
** [[Chilomastix|Chilomastigida]]
** [[Retortamonad]]ida
** [[Retortamonad]]ida
** [[Diplomonad]]ida
** [[Diplomonad]]ida
⚫
| synonyms_ref = <ref name="Al Jewari Baldauf 2023"/>
⚫
| synonyms =
* ?[[Archezoa]]
* Centrosomea <small>Chatton Villeneuve 1937</small>
⚫
* Metamonadina <small>Grassé 1952</small>
* Polymastigota <small>Butschli 1884</small>
* Tetramastigota <small>Hulsmann & Hausmann 1994</small>
}}
}}


The '''metamonads''' are a large group of [[flagellate]] [[amitochondriate]] microscopic [[eukaryote]]s. Their composition is not entirely settled, but they include the [[retortamonad]]s, [[diplomonad]]s, and possibly the [[parabasalid]]s and [[oxymonad]]s as well. These four groups are all [[Anaerobic organism|anaerobic]] (many being aerotolerant anaerobes), occurring mostly as [[symbiosis|symbiote]]s or [[parasitism|parasite]]s of animals, as is the case with [[Giardia duodenalis|''Giardia lamblia'']] which causes diarrhea in [[mammal]]s.<ref name="Al Jewari Baldauf 2023">{{Cite journal |last=Al Jewari |first=Caesar |last2=Baldauf |first2=Sandra L. |date=2023-04-28 |title=An excavate root for the eukaryote tree of life |url=https://www.science.org/doi/10.1126/sciadv.ade4973 |journal=Science Advances |volume=9 |issue=17 |pages=eade4973 |doi=10.1126/sciadv.ade4973 |issn=2375-2548 |pmc=10146883 |pmid=37115919}}</ref>
The '''metamonads''' are a large group of [[flagellate]] [[amitochondriate]] microscopic [[eukaryote]]s. Their composition is not entirely settled, but they include the [[retortamonad]]s, [[diplomonad]]s, and possibly the [[parabasalid]]s and [[oxymonad]]s as well. These four groups are all [[Anaerobic organism|anaerobic]] (many being aerotolerant anaerobes), occurring mostly as [[symbiosis|symbiote]]s or [[parasitism|parasite]]s of animals, as is the case with [[Giardia duodenalis|''Giardia lamblia'']] which causes diarrhea in [[mammal]]s.<ref name="Al Jewari Baldauf 2023">{{Cite journal |last1=Al Jewari |first1=Caesar |last2=Baldauf |first2=Sandra L. |date=2023-04-28 |title=An excavate root for the eukaryote tree of life |journal=Science Advances |volume=9 |issue=17 |pages=eade4973 |doi=10.1126/sciadv.ade4973 |issn=2375-2548 |pmc=10146883 |pmid=37115919|bibcode=2023SciA....9E4973A }}</ref>


==Characteristics==
==Characteristics==
A number of parabasalids and oxymonads are found in [[termite]] [[guts]], and play an important role in breaking down the [[cellulose]] found in [[wood]]. Some other metamonads are [[Parasitism|parasites]].
A number of parabasalids and oxymonads are found in [[termite]] [[guts]], and play an important role in breaking down the [[cellulose]] found in [[wood]]. Some other metamonads are [[Parasitism|parasites]].


These flagellates are unusual in lacking [[mitochondrion|mitochondria]]. Originally they were considered among the most primitive [[eukaryote]]s, diverging from the others before mitochondria appeared. However, they are now known to have lost mitochondria secondarily, and retain both organelles and nuclear genes derived from them. Mitochondrial relics include [[hydrogenosome]]s, which produce [[hydrogen]], and small structures called [[mitosome]]s.
These flagellates are unusual in lacking [[mitochondrion|mitochondria]]. Originally they were considered among the most primitive [[eukaryote]]s, diverging from the others before mitochondria appeared. However, they are now known to have lost mitochondria secondarily, and retain both organelles and nuclear genes derived from them. Mitochondrial relics include [[hydrogenosome]]s, which produce [[hydrogen]], and small structures called [[mitosome]]s.


It now appears the Metamonada are, together with ''[[Malawimonas]]'', sister clades of the [[Unikont|Podiata]].<ref>{{Cite journal|last1=Cavalier-Smith|first1=Thomas|last2=Chao|first2=Ema E.|last3=Lewis|first3=Rhodri|date=2016-06-01|title=187-gene phylogeny of protozoan phylum Amoebozoa reveals a new class (Cutosea) of deep-branching, ultrastructurally unique, enveloped marine Lobosa and clarifies amoeba evolution|journal=Molecular Phylogenetics and Evolution|volume=99|pages=275–296|doi=10.1016/j.ympev.2016.03.023|pmid=27001604|doi-access=free}}</ref>
It now appears the Metamonada are, together with ''[[Malawimonas]]'', sister clades of the [[Unikont|Podiata]].<ref>{{Cite journal|last1=Cavalier-Smith|first1=Thomas|last2=Chao|first2=Ema E.|last3=Lewis|first3=Rhodri|date=2016-06-01|title=187-gene phylogeny of protozoan phylum Amoebozoa reveals a new class (Cutosea) of deep-branching, ultrastructurally unique, enveloped marine Lobosa and clarifies amoeba evolution|journal=Molecular Phylogenetics and Evolution|volume=99|pages=275–296|doi=10.1016/j.ympev.2016.03.023|pmid=27001604|doi-access=free}}</ref>


All of these groups are united by having [[flagellum|flagella]] or basal bodies in characteristic groups of four, which are often associated with the [[cell nucleus|nucleus]], forming a structure called a ''karyomastigont''. In addition, the genera ''Carpediemonas'' and ''Trimastix'' are now known to be close relatives of the retortamonad-diplomonad line and the oxymonads, respectively. Both are free-living and amitochondriate.
All of these groups are united by having [[flagellum|flagella]] or basal bodies in characteristic groups of four, which are often associated with the [[cell nucleus|nucleus]], forming a structure called a karyomastigont. In addition, the genera ''[[Carpediemonas]]'' and ''[[Trimastix]]'' are now known to be close relatives of the retortamonad-diplomonad line and the oxymonads, respectively. Both are free-living and amitochondriate.


== Classification ==
== Classification ==
The metamonads were thought to make up part of the [[Excavata]], a paraphyletic eukaryotic supergroup including flagellates with feeding grooves and their close relatives. Their relationships are uncertain,<ref name="pmid14657102">{{cite journal |author=Cavalier-Smith T |title=The excavate protozoan phyla Metamonada Grassé emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa |journal=Int. J. Syst. Evol. Microbiol. |volume=53 |issue=Pt 6 |pages=1741–58 |date=November 2003 |pmid=14657102 |doi= 10.1099/ijs.0.02548-0|url=http://ijs.sgmjournals.org/cgi/pmidlookup?view=long&pmid=14657102|doi-access=free }}</ref> and they do not always appear together on molecular trees. It is possible that the metamonads as defined here do not form a [[monophyletic]] subgroup.
The metamonads were thought to make up part of the [[Excavata]], a paraphyletic eukaryotic supergroup including flagellates with feeding grooves and their close relatives. Their relationships are uncertain,<ref name="pmid14657102">{{cite journal |author=Cavalier-Smith T |title=The excavate protozoan phyla Metamonada Grassé emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa |journal=Int. J. Syst. Evol. Microbiol. |volume=53 |issue=Pt 6 |pages=1741–58 |date=November 2003 |pmid=14657102 |doi= 10.1099/ijs.0.02548-0|doi-access=free }}</ref> and they do not always appear together on molecular trees. It is possible that the metamonads as defined here do not form a [[monophyletic]] subgroup.


The following higher level treatment from 2013 is based on works of Cavalier-Smith<ref>{{cite journal |author=Cavalier-Smith T |title=Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa |journal= Eur. J. Protistol. |volume=49 |issue=2 |pages=115–178 |date= 2013 |pmid=23085100 |doi=10.1016/j.ejop.2012.06.001 }}</ref> with amendments within Fornicata from Yubukia, Simpson & Leander.<ref>{{cite journal |author1=Yubukia |author2=Simpson |author3=Leander |title=Comprehensive Ultrastructure of Kipferlia bialata Provides Evidence for Character Evolution within the Fornicata (Excavata) |journal=Protist |volume= 164|issue= 3|pages= 423–439|date= 2013 |pmid= 23517666|doi=10.1016/j.protis.2013.02.002 }}</ref>
The following higher level treatment from 2013 is based on works of [[Thomas Cavalier-Smith|Cavalier-Smith]]<ref>{{cite journal |author=Cavalier-Smith T |title=Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa |journal= Eur. J. Protistol. |volume=49 |issue=2 |pages=115–178 |date= 2013 |pmid=23085100 |doi=10.1016/j.ejop.2012.06.001 }}</ref> with amendments within [[Fornicata]] from Yubukia, Simpson & Leander.<ref>{{cite journal |author1=Yubukia |author2=Simpson |author3=Leander |title=Comprehensive Ultrastructure of Kipferlia bialata Provides Evidence for Character Evolution within the Fornicata (Excavata) |journal=Protist |volume= 164|issue= 3|pages= 423–439|date= 2013 |pmid= 23517666|doi=10.1016/j.protis.2013.02.002 }}</ref>


Metamonada were once again proposed to be basal eukaryotes in 2018.<ref>{{Cite journal|last1=Krishnan|first1=Arunkumar|last2=Burroughs|first2=A. Max |last3=Iyer |first3=Lakshminarayan|last4=Aravind|first4=L.|date=2018-07-04|title=The unexpected provenance of components in eukaryotic nucleotide-excision-repair and kinetoplast DNA-dynamics from bacterial mobile elements|url=https://www.biorxiv.org/content/early/2018/07/04/361121|journal=bioRxiv |pages=361121 |doi=10.1101/361121 |doi-access=free}}</ref>
Metamonada were once again proposed to be basal eukaryotes in 2018.<ref>{{Cite journal|last1=Krishnan|first1=Arunkumar|last2=Burroughs|first2=A. Max |last3=Iyer |first3=Lakshminarayan|last4=Aravind|first4=L.|date=2018-07-04|title=The unexpected provenance of components in eukaryotic nucleotide-excision-repair and kinetoplast DNA-dynamics from bacterial mobile elements|url=https://www.biorxiv.org/content/early/2018/07/04/361121|journal=bioRxiv |pages=361121 |doi=10.1101/361121 |doi-access=free}}</ref>


* Phylum '''Metamonada''' <small>(Grassé 1952) Cavalier-Smith 1987 emend. Cavalier-Smith 2003</small>
* Phylum '''Metamonada''' <small>(Grassé 1952) Cavalier-Smith 1987 emend. Cavalier-Smith 2003</small>
** Family [[Anaeramoebidae]] <small>Táborský, Pánek & Čepička 2017</small>
** Subphylum [[Anaeromonada]] <small>Cavalier-Smith 1997 emend. 2003</small>
** Subphylum [[Anaeromonada]] <small>Cavalier-Smith 1997 emend. 2003</small>
*** Class [[Anaeromonadea]] <small>Cavalier-Smith 1997 emend. 1999</small>
*** Class [[Anaeromonadea]] <small>Cavalier-Smith 1997 emend. 1999</small>
**** Family [[Paratrimastigidae]] <small>Zhang et al. 2015</small><ref>{{Cite journal |last1=Zhang |first1=Qianqian |last2=Táborský |first2=Petr |last3=Silberman |first3=Jeffrey D. |last4=Pánek |first4=Tomáš |last5=Čepička |first5=Ivan |last6=Simpson|first6=Alastair G.B. |year=2015 |title=Marine Isolates of Trimastix marina Form a Plesiomorphic Deep-branching Lineage within Preaxostyla, Separate from Other Known Trimastigids (Paratrimastix n. gen.) |url=https://www.sciencedirect.com/science/article/abs/pii/S1434461015000462 |journal=Protist |volume=166 |issue=4 |pages=468–491 |doi=10.1016/j.protis.2015.07.003 |doi-access=|pmid=26312987 }}</ref>
⚫
**** Family [[Paratrimastigidae]] <small>Zhang et al. 2015</small>
**** Order [[Trimastix|Trimastigida]] <small>Cavalier-Smith 2003</small>
**** Order [[Trimastix|Trimastigida]] <small>Cavalier-Smith 2003</small>
***** Family [[Trimastix|Trimastigidae]] <small>Saville Kent 1880</small>
***** Family [[Trimastix|Trimastigidae]] <small>Saville Kent 1880</small>
Line 51: Line 58:
***** Family [[Saccinobaculidae]] <small>Brugerolle & Lee 2002 ex Cavalier-Smith 2013</small>
***** Family [[Saccinobaculidae]] <small>Brugerolle & Lee 2002 ex Cavalier-Smith 2013</small>
***** Family [[Pyrsonymphidae]] <small>Grassé 1892</small>
***** Family [[Pyrsonymphidae]] <small>Grassé 1892</small>
⚫
***** Family [[Streblomastigidae]] <small>Kofoid & Swezy 1919</small>
***** Family [[Oxymonadidae]] <small>Kirby 1928</small>
***** Family [[Oxymonadidae]] <small>Kirby 1928</small>
** Subphylum [[Trichozoa]] <small>Cavalier-Smith 1996 emend. Cavalier-Smith 2003 stat. n. 2013</small>
** Subphylum [[Trichozoa]] <small>Cavalier-Smith 1996 emend. Cavalier-Smith 2003 stat. n. 2013</small>
*** Superclass [[Fornicata]] <small>Simpson 2003 stat. n. Cavalier-Smith 2013</small>
*** Superclass [[Fornicata]] <small>Simpson 2003 stat. n. Cavalier-Smith 2013</small>
**** Genus ''[[Ergobibamus]]''
**** Genus ''[[Hicanonectes]]''
**** Family [[Kipferliidae]] <small>Cavalier-Smith 2013</small>
**** Family [[Kipferliidae]] <small>Cavalier-Smith 2013</small>
⚫
**** Order [[Chilomastigida]] <small>Cavalier-Smith 2013</small>
⚫
***** Family [[Chilomastigidae]] <small>Cavalier-Smith 2013</small>
⚫
**** Order [[Dysnectida]] <small>Cavalier-Smith 2013</small>
⚫
***** Family [[Dysnectidae]] <small>Cavalier-Smith 2013</small>
**** Class [[Carpediemonadea]] <small>Cavalier-Smith 2013 s.s.</small>
**** Class [[Carpediemonadea]] <small>Cavalier-Smith 2013 s.s.</small>
***** Order [[Carpediemonadida]] <small>Cavalier-Smith 2003 emend. 2013 s.s.</small>
***** Order [[Carpediemonadida]] <small>Cavalier-Smith 2003 emend. 2013 s.s.</small>
****** Family [[Carpediemonadidae]] <small>Cavalier-Smith 2003</small>
****** Family [[Carpediemonadidae]] <small>Cavalier-Smith 2003</small>
**** Class [[Eopharyngea]] <small>Cavalier-Smith 1993 stat. n. Cavalier-Smith 2003</small>
**** Class [[Eopharyngea]] <small>Cavalier-Smith 1993 stat. n. Cavalier-Smith 2003</small>
⚫
***** Order [[Dysnectida]] <small>Cavalier-Smith 2013</small>
⚫
****** Family [[Dysnectidae]] <small>Cavalier-Smith 2013</small>
***** Order [[Retortamonadida]] <small>Grassé 1952 emend. Cavalier-Smith 2013</small>
***** Order [[Retortamonadida]] <small>Grassé 1952 emend. Cavalier-Smith 2013</small>
⚫
****** Family [[Caviomonadidae]] <small>Cavalier-Smith 2013</small>
⚫
****** Family [[Chilomastix|Chilomastigidae]] <small>Cavalier-Smith 2013</small>
****** Family [[Retortamonadidae]] <small>Wenrich 1932</small>
****** Family [[Retortamonadidae]] <small>Wenrich 1932</small>
***** Order [[Diplomonadida]] <small>Wenyon 1926 emend. Brugerolle et al. 1975</small>
***** Order [[Diplomonadida]] <small>Wenyon 1926 emend. Brugerolle et al. 1975</small>
Line 74: Line 78:
****** Family [[Hexamitidae]] <small>Kent 1880 emend. Brugerolle et al. 1975</small>
****** Family [[Hexamitidae]] <small>Kent 1880 emend. Brugerolle et al. 1975</small>
*** Superclass [[Parabasalia]] <small>Honigberg 1973 stat. n. Cavalier-Smith 2003</small>
*** Superclass [[Parabasalia]] <small>Honigberg 1973 stat. n. Cavalier-Smith 2003</small>
**** Class [[Chilomitea]]
***** Order [[Chilomitida]]
****** Family [[Chilomitidae]]
**** Class [[Trichonymphea]] <small>Cavalier-Smith 2003</small>
**** Class [[Trichonymphea]] <small>Cavalier-Smith 2003</small>
***** Order [[Lophomonadida]] <small>Light 1927</small>
***** Order [[Lophomonadida]] <small>Light 1927</small>
****** Family [[Lophomonadidae]] <small>Saville Kent 1880</small>
****** Family [[Lophomonadidae]] <small>Saville Kent 1880</small>
***** Order [[Trichonymphida]] <small>Poche 1913</small>
***** Order [[Trichonymphida]] <small>Poche 1913</small>
⚫
****** Family †[[Burmanymphidae]] <small>Poinar 2009</small>
****** Family [[Retractinymphidae]] <small>Radek & Brune 2023</small><ref>{{cite journal |last1=Radek |first1=Renate |last2=Platt |first2=Katja |last3=Öztas |first3=Deniz |last4=Šobotník |first4=Jan |last5=Sillam-Dussès |first5=David |last6=Hanus |first6=Robert |last7=Brune |first7=Andreas |title=New insights into the coevolutionary history of termites and their gut flagellates: Description of Retractinympha glossotermitis gen. nov. sp. nov. (Retractinymphidae fam. nov.) |journal=Frontiers in Ecology and Evolution |date=26 January 2023 |volume=11 |doi=10.3389/fevo.2023.1111484 |doi-access=free |url=https://www.researchgate.net/publication/367441669}}</ref>
****** Family [[Spirotrichosomidae]] <small>Hollande & Caruette-Valentin 1971</small>
****** Family [[Spirotrichosomidae]] <small>Hollande & Caruette-Valentin 1971</small>
****** Family [[Staurojoeninidae]] <small>Grassé 1917</small>
****** Family [[Staurojoeninidae]] <small>Grassé 1917</small>
****** Family [[Trichonymphidae]] <small>Saville Kent 1880</small>
****** Family [[Trichonymphidae]] <small>Saville Kent 1880</small>
****** Family [[Hoplonymphidae]] <small>Light 1926</small>
****** Family [[Hoplonymphidae]] <small>Light 1926</small>
****** Family [[Teranymphidae]] <small>Koidzumi 1921</small> [Eucomonymphidae]
****** Family [[Teratonymphidae]] <small>Koidzumi 1921</small> [Eucomonymphidae]
**** Class [[Trichomonadea]] <small>Kirby 1947 stat. n. Cavalier-Smith 2003</small>
**** Class [[Trichomonadea]] <small>Kirby 1947 stat. n. Cavalier-Smith 2003</small>
***** Order [[Pimpavickida]] <small>Céza & Čepička 2022</small><ref name="Céza_2022">{{cite journal |last1=Céza |first1=Vít |last2=Kotyk |first2=Michael |last3=Kubánková |first3=Aneta |last4=Yubuki |first4=Naoji |last5=Šťáhlavský |first5=František |last6=Silberman |first6=Jeffrey D. |last7=Čepička |first7=Ivan |title=Free-living Trichomonads are Unexpectedly Diverse |journal=Protist |date=August 2022 |volume=173 |issue=4 |pages=125883 |doi=10.1016/j.protis.2022.125883|pmid=35660751 |s2cid=248586911 }}</ref>
***** Order [[Trichocovinida]]
****** Family [[Trichocovinidae]]
****** Family [[Pimpavickidae]] <small>Céza & Čepička 2022</small>
***** Order [[Trichomonadida]] <small>Kirby 1947</small>
***** Order [[Trichomonadida]] <small>Kirby 1947</small>
****** Suborder [[Hypotrichomonadina]] <small>Čepička et al. 2010 stat. n.</small>
****** Family [[Lacusteriidae]] <small>Céza & Čepička 2022</small><ref name="Céza_2022"/>
******* Family [[Hypotrichomonadidae]] <small>(Honigberg 1963) Čepička, Hampl & Kulda 2010 </small>
****** Family [[Trichomonadidae]] <small>Chalmers & Pekkoloa 1918 sensu Hampl et al. 2006</small>
***** Order [[Honigbergiellida]] <small>Čepička et al. 2010</small><ref>{{cite journal |last1=Cepicka |first1=Ivan |last2=Hampl |first2=Vladimír |last3=Kulda |first3=Jaroslav |title=Critical Taxonomic Revision of Parabasalids with Description of one New Genus and three New Species |journal=Protist |date=July 2010 |volume=161 |issue=3 |pages=400–433 |doi=10.1016/j.protis.2009.11.005|pmid=20093080 }}</ref><ref name="Céza_2022"/>
****** Suborder [[Trichomonadina]] <small>(Kirby 1947) Cavalier-Smith 2013</small>
******* Family [[Trichomonadidae]] <small>Chalmers & Pekkoloa 1918 sensu Hampl et al. 2006</small>
****** Family [[Honigbergiellidae]] <small>Čepička, Hampl & Kulda 2010</small>
****** Suborder [[Honigbergiellina]] <small>Čepička et al. 2010</small>
****** Family [[Hexamastigidae]] <small>Čepička, Hampl & Kulda 2010</small>
******* Family [[Honigbergiellidae]] <small>Čepička, Hampl & Kulda 2010</small>
****** Family [[Tricercomitidae]] <small>Čepička, Hampl & Kulda 2010</small>
******* Family [[Hexamastigidae]] <small>Čepička, Hampl & Kulda 2010</small>
***** Order [[Hypotrichomonadida]] <small>Čepička et al. 2010</small>
******* Family [[Tricercomitidae]] <small>Čepička, Hampl & Kulda 2010</small>
****** Family [[Hypotrichomonadidae]] <small>(Honigberg 1963) Čepička, Hampl & Kulda 2010 </small>
***** Order [[Spirotrichonymphida]] <small>Grassé 1952</small>
⚫
****** Family [[Spirotrichonymphidae]] <small>Grassé 1917</small>
***** Order [[Tritrichomonadida]] <small>Čepička et al. 2010</small>
***** Order [[Tritrichomonadida]] <small>Čepička et al. 2010</small>
****** Family [[Dientamoebidae]] <small>Grassé 1953</small>
****** Family [[Dientamoebidae]] <small>Grassé 1953</small>
Line 103: Line 108:
****** Family [[Simplicimonadidae]] <small>Čepička et al. 2010</small>
****** Family [[Simplicimonadidae]] <small>Čepička et al. 2010</small>
****** Family [[Tritrichomonadidae]] <small>Honigberg 1963</small>
****** Family [[Tritrichomonadidae]] <small>Honigberg 1963</small>
***** Subclass [[Cristomonadia]] <small>Cavalier-Smith, 2013</small>
***** Order [[Cristamonadida]] <small>Brugerolle & Patterson 2001 emend. Cavalier-Smith 2013</small>
****** Order [[Spirotrichonymphida]] <small>Grassé 1952</small>
****** Family [[Calonymphidae]] <small>Grassé 1911</small>
******* Family [[Spirotrichonymphidae]] <small>Grassé 1917</small>
****** Family [[Devescovinidae]] <small>Doflein 1911</small>
****** Order [[Cristamonadida]] <small>Brugerolle & Patterson 2001 emend. Cavalier-Smith 2013</small>
⚫
******* Family [[Calonymphidae]] <small>Grassé 1911</small>
******* Family [[Devescovinidae]] <small>Doflein 1911</small> [Joeniidae; Rhizonymphidae; Kofoidiidae; Deltotrichonymphidae]


== References ==
== References ==

Latest revision as of 20:32, 14 April 2024

For an explanation of very similar terms, see Excavata.

Metamonad
"Giardia lamblia", a parasitic diplomonad
Giardia lamblia, a parasitic diplomonad
Scientific classification Edit this classification
Domain: Eukaryota
(unranked): Excavata
Phylum: Metamonada
Grassé 1952 emend. Cavalier-Smith 2003
Classes & orders
Synonyms[2]
  • ?Archezoa
  • Centrosomea Chatton Villeneuve 1937
  • Metamonadina Grassé 1952
  • Polymastigota Butschli 1884
  • Tetramastigota Hulsmann & Hausmann 1994

The metamonads are a large group of flagellate amitochondriate microscopic eukaryotes. Their composition is not entirely settled, but they include the retortamonads, diplomonads, and possibly the parabasalids and oxymonads as well. These four groups are all anaerobic (many being aerotolerant anaerobes), occurring mostly as symbiotes or parasites of animals, as is the case with Giardia lamblia which causes diarrhea in mammals.[2]

Characteristics[edit]

A number of parabasalids and oxymonads are found in termite guts, and play an important role in breaking down the cellulose found in wood. Some other metamonads are parasites.

These flagellates are unusual in lacking mitochondria. Originally they were considered among the most primitive eukaryotes, diverging from the others before mitochondria appeared. However, they are now known to have lost mitochondria secondarily, and retain both organelles and nuclear genes derived from them. Mitochondrial relics include hydrogenosomes, which produce hydrogen, and small structures called mitosomes.

It now appears the Metamonada are, together with Malawimonas, sister clades of the Podiata.[3]

All of these groups are united by having flagella or basal bodies in characteristic groups of four, which are often associated with the nucleus, forming a structure called a karyomastigont. In addition, the genera Carpediemonas and Trimastix are now known to be close relatives of the retortamonad-diplomonad line and the oxymonads, respectively. Both are free-living and amitochondriate.

Classification[edit]

The metamonads were thought to make up part of the Excavata, a paraphyletic eukaryotic supergroup including flagellates with feeding grooves and their close relatives. Their relationships are uncertain,[4] and they do not always appear together on molecular trees. It is possible that the metamonads as defined here do not form a monophyletic subgroup.

The following higher level treatment from 2013 is based on works of Cavalier-Smith[5] with amendments within Fornicata from Yubukia, Simpson & Leander.[6]

Metamonada were once again proposed to be basal eukaryotes in 2018.[7]

References[edit]

  1. ^ Stairs, Courtney W.; Táborský, Petr; Salomaki, Eric D.; Kolisko, Martin; Pánek, Tomáš; Eme, Laura; Hradilová, Miluše; Vlček, Čestmír; Jerlström-Hultqvist, Jon; Roger, Andrew J.; Čepička, Ivan (2021-12-20). "Anaeramoebae are a divergent lineage of eukaryotes that shed light on the transition from anaerobic mitochondria to hydrogenosomes". Current Biology. 31 (24): 5605–5612.e5. doi:10.1016/j.cub.2021.10.010. ISSN 0960-9822. PMID 34710348. S2CID 240054026.
  2. ^ a b Al Jewari, Caesar; Baldauf, Sandra L. (2023-04-28). "An excavate root for the eukaryote tree of life". Science Advances. 9 (17): eade4973. Bibcode:2023SciA....9E4973A. doi:10.1126/sciadv.ade4973. ISSN 2375-2548. PMC 10146883. PMID 37115919.
  3. ^ Cavalier-Smith, Thomas; Chao, Ema E.; Lewis, Rhodri (2016-06-01). "187-gene phylogeny of protozoan phylum Amoebozoa reveals a new class (Cutosea) of deep-branching, ultrastructurally unique, enveloped marine Lobosa and clarifies amoeba evolution". Molecular Phylogenetics and Evolution. 99: 275–296. doi:10.1016/j.ympev.2016.03.023. PMID 27001604.
  4. ^ Cavalier-Smith T (November 2003). "The excavate protozoan phyla Metamonada Grassé emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa". Int. J. Syst. Evol. Microbiol. 53 (Pt 6): 1741–58. doi:10.1099/ijs.0.02548-0. PMID 14657102.
  5. ^ Cavalier-Smith T (2013). "Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa". Eur. J. Protistol. 49 (2): 115–178. doi:10.1016/j.ejop.2012.06.001. PMID 23085100.
  6. ^ Yubukia; Simpson; Leander (2013). "Comprehensive Ultrastructure of Kipferlia bialata Provides Evidence for Character Evolution within the Fornicata (Excavata)". Protist. 164 (3): 423–439. doi:10.1016/j.protis.2013.02.002. PMID 23517666.
  7. ^ Krishnan, Arunkumar; Burroughs, A. Max; Iyer, Lakshminarayan; Aravind, L. (2018-07-04). "The unexpected provenance of components in eukaryotic nucleotide-excision-repair and kinetoplast DNA-dynamics from bacterial mobile elements". bioRxiv: 361121. doi:10.1101/361121.
  8. ^ Zhang, Qianqian; Táborský, Petr; Silberman, Jeffrey D.; Pánek, Tomáš; Čepička, Ivan; Simpson, Alastair G.B. (2015). "Marine Isolates of Trimastix marina Form a Plesiomorphic Deep-branching Lineage within Preaxostyla, Separate from Other Known Trimastigids (Paratrimastix n. gen.)". Protist. 166 (4): 468–491. doi:10.1016/j.protis.2015.07.003. PMID 26312987.
  9. ^ Radek, Renate; Platt, Katja; Öztas, Deniz; Šobotník, Jan; Sillam-Dussès, David; Hanus, Robert; Brune, Andreas (26 January 2023). "New insights into the coevolutionary history of termites and their gut flagellates: Description of Retractinympha glossotermitis gen. nov. sp. nov. (Retractinymphidae fam. nov.)". Frontiers in Ecology and Evolution. 11. doi:10.3389/fevo.2023.1111484.
  10. ^ a b c Céza, Vít; Kotyk, Michael; Kubánková, Aneta; Yubuki, Naoji; Šťáhlavský, František; Silberman, Jeffrey D.; Čepička, Ivan (August 2022). "Free-living Trichomonads are Unexpectedly Diverse". Protist. 173 (4): 125883. doi:10.1016/j.protis.2022.125883. PMID 35660751. S2CID 248586911.
  11. ^ Cepicka, Ivan; Hampl, Vladimír; Kulda, Jaroslav (July 2010). "Critical Taxonomic Revision of Parabasalids with Description of one New Genus and three New Species". Protist. 161 (3): 400–433. doi:10.1016/j.protis.2009.11.005. PMID 20093080.

External links[edit]

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