View source for Apusozoa

{{Short description|Phylum of micro-organisms}}
{{For|the monophyletic counterpart|Obazoa}}
{{Paraphyletic group
| auto = yes
| display_parents = 3
| image = Apusomonas.png
| image_alt = Apusomonas sp.
| image_caption = ''[[Apusomonas]]'' sp.
| taxon = Apusozoa
| authority = [[Thomas Cavalier-Smith|Cavalier-Smith]] 1997 emend. 2013
| includes =
*[[Thecomonadea]]
*[[Breviatea]]
| excludes =
* [[Opisthokonta]]
| color_as = Eukaryota
| classification_status = obsolete
}}

The '''Apusozoa''' are a [[paraphyletic]] [[phylum (biology)|phylum]]<ref name="pmid18723395">{{cite journal |vauthors=Cavalier-Smith T, Chao EE, Stechmann A, Oates B, Nikolaev S |title=Planomonadida ord. nov. (Apusozoa): ultrastructural affinity with Micronuclearia podoventralis and deep divergences within Planomonas gen. nov |journal=Protist |volume=159 |issue=4 |pages=535–62 |date=October 2008 |pmid=18723395 |doi=10.1016/j.protis.2008.06.002 }}</ref> of [[flagellate]] [[eukaryotes]]. They are usually around 5–20 μm in size, and occur in soils and aquatic habitats, where they feed on [[bacterium|bacteria]]. They are grouped together based on the presence of an organic shell or [[theca]] under the dorsal surface of the cell.

The name derives from the Ancient Greek words for footless ({{Lang|el|ἄπους}}) and animal ({{Lang|el|ζῷον}}).<ref>{{LSJ|apous|ἄπους|cite}}</ref><ref>{{LSJ|zwon|ζῷον|cite}}</ref>

This phylum was defined as containing the [[Breviata]] and the [[Apusomonadida]].<ref>{{Cite journal|last1=Eme|first1=Laura|last2=Sharpe|first2=Susan C.|last3=Brown|first3=Matthew W.|last4=Roger|first4=Andrew J.|date=2014-08-01|title=On the Age of Eukaryotes: Evaluating Evidence from Fossils and Molecular Clocks|journal=Cold Spring Harbor Perspectives in Biology|language=en|volume=6|issue=8|pages=a016139|doi=10.1101/cshperspect.a016139|issn=1943-0264|pmid=25085908|pmc=4107988}}</ref><ref>{{Cite journal|last1=Ruggiero|first1=Michael A.|last2=Gordon|first2=Dennis P.|last3=Orrell|first3=Thomas M.|last4=Bailly|first4=Nicolas|last5=Bourgoin|first5=Thierry|last6=Brusca|first6=Richard C.|last7=Cavalier-Smith|first7=Thomas|last8=Guiry|first8=Michael D.|last9=Kirk|first9=Paul M.|date=2015-06-11|title=Correction: A Higher Level Classification of All Living Organisms|journal=PLOS ONE|volume=10|issue=6|pages=e0130114|doi=10.1371/journal.pone.0130114|pmid=26068874|pmc=5159126|bibcode=2015PLoSO..1030114R|issn=1932-6203|doi-access=free}}</ref> However, it is viewed as paraphyletic, with the Breviata as more basal. The opisthokonts appear to have emerged as sister of the Apusomonadida. It has been suggested that the [[Mantamonadida]] be classified in Apusozoa.<ref name="pmid20884290">{{cite journal|date=September 2010|title=The Novel Marine Gliding Zooflagellate Genus Mantamonas (Mantamonadida ord. n.: Apusozoa)|journal=Protist|volume=162|issue=2|pages=207–221|doi=10.1016/j.protis.2010.06.004|pmid=20884290|vauthors=Glücksman E, Snell EA, Berney C, Chao EE, Bass D, Cavalier-Smith T}}</ref><ref>{{cite bioRxiv|last1=Orr|first1=Russell J. S.|last2=Zhao|first2=Sen|last3=Klaveness|first3=Dag|last4=Yabuki|first4=Akinori|last5=Ikeda|first5=Keiji|last6=Makoto|first6=Watanabe M.|last7=Shalchian-Tabrizi|first7=Kamran|date=2017-10-08|title=Enigmatic Diphyllatea eukaryotes: Culturing and targeted PacBio RS amplicon sequencing reveals a higher order taxonomic diversity and global distribution|biorxiv=10.1101/199125}}</ref>

The [[Ancyromonadida]] appear to be [[Varisulca]], Planomonadida, shifting them possibly more basal than the Amoebozoa,<ref>{{Cite journal|last1=Speijer|first1=Dave|last2=Lukeš|first2=Julius|last3=Eliáš|first3=Marek|date=2015-07-21|title=Sex is a ubiquitous, ancient, and inherent attribute of eukaryotic life|journal=Proceedings of the National Academy of Sciences|language=en|volume=112|issue=29|pages=8827–8834|doi=10.1073/pnas.1501725112|issn=0027-8424|pmid=26195746|pmc=4517231|bibcode=2015PNAS..112.8827S|doi-access=free}}</ref><ref>{{Cite journal|last1=Torruella|first1=Guifré|last2=Mendoza|first2=Alex de|last3=Grau-Bové|first3=Xavier|last4=Antó|first4=Meritxell|last5=Chaplin|first5=Mark A.|last6=Campo|first6=Javier del|last7=Eme|first7=Laura|last8=Pérez-Cordón|first8=Gregorio|last9=Whipps|first9=Christopher M.|title=Phylogenomics Reveals Convergent Evolution of Lifestyles in Close Relatives of Animals and Fungi|journal=Current Biology|volume=25|issue=18|pages=2404–2410|doi=10.1016/j.cub.2015.07.053|pmid=26365255|year=2015|doi-access=free}}</ref><ref>{{Cite journal|last1=Cavalier-Smith|first1=Thomas|last2=Chao|first2=Ema E.|last3=Snell|first3=Elizabeth A.|last4=Berney|first4=Cédric|last5=Fiore-Donno|first5=Anna Maria|last6=Lewis|first6=Rhodri|title=Multigene eukaryote phylogeny reveals the likely protozoan ancestors of opisthokonts (animals, fungi, choanozoans) and Amoebozoa|journal=Molecular Phylogenetics and Evolution|volume=81|pages=71–85|doi=10.1016/j.ympev.2014.08.012|pmid=25152275|year=2014|doi-access=free}}</ref> or less basal.<ref>{{Cite journal|last1=Paps|first1=Jordi|last2=Medina-Chacón|first2=Luis A.|last3=Marshall|first3=Wyth|last4=Suga|first4=Hiroshi|last5=Ruiz-Trillo|first5=Iñaki|title=Molecular Phylogeny of Unikonts: New Insights into the Position of Apusomonads and Ancyromonads and the Internal Relationships of Opisthokonts|journal=Protist|volume=164|issue=1|pages=2–12|doi=10.1016/j.protis.2012.09.002|pmid=23083534|pmc=4342546|year=2013}}</ref> While some classification systems have placed [[Hemimastigida]] in Apusozoa,<ref>{{Cite journal|date=2003-01-01|title=Protist phylogeny and the high-level classification of Protozoa|journal=European Journal of Protistology|language=en|volume=39|issue=4|pages=338–348|doi=10.1078/0932-4739-00002|issn=0932-4739|last1=Cavalier-Smith|first1=Thomas}}</ref> 2018 research indicated that [[hemimastigote]]s ({{ill|Hemimastix kukwesjijk|de}}/[[Hemimastix]]/[[Spironematellidae]]) are their own [[supra-kingdom]].<ref>{{cite news |last1=Chung |first1=Emily |title=Rare microbes lead scientists to discover new branch on the tree of life |url=https://www.cbc.ca/news/technology/hemimastigotes-supra-kingdom-1.4715823 |access-date=16 November 2018 |agency=CBC news |date=November 16, 2018}}</ref>

==Characteristics==
The apusomonads have two flagella inserted at right angles, near the anterior of the cell.  They move by gliding, with one flagellum trailing along the side and one directed to the anterior.

The form of the [[mitochondrion|mitochondria]] varies between the different orders.  Among the apusomonads they have tubular [[crista]]e, the ancyromonads flat cristae, and the hemimastigids ambiguous or sacculate cristae.  This characteristic was originally considered a good indicator of relationships, but is now known to vary even among close relatives.
==Evolution==
As currently defined, Apusozoa is a [[paraphyletic]] [[Evolutionary grade|grade]] that includes two classes: [[Thecomonadea]] (the apusomonad flagellates) and [[Breviatea]] (the breviate amoebae),<ref name="CavSmith 2021">{{cite journal|vauthors=Cavalier-Smith T|title=Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi|journal=Protoplasma|doi=10.1007/s00709-021-01665-7|date=December 2021|volume=259|pages=487–593|pmc=9010356}}</ref> each of them [[monophyletic]] and [[sister group]]s to the [[Opisthokonta]] [[supergroup (biology)|supergroup]]. Together, these three clades are part of the larger clade [[Obazoa]], which in turn is the sister group to the [[Amoebozoa]] supergroup.<ref name="EUBAC">{{citation|vauthors=Derelle R, Torruella G, Klimeš V, Brinkmann H, Kim E, Vlček Č, Lang BF, Eliáš M|title=Bacterial proteins pinpoint a single eukaryotic root|journal=Proc Natl Acad Sci U S A|date=2015|volume=112|issue=7|pages=E693–699|doi=10.1073/pnas.1420657112|pmid=25646484|pmc=4343179|bibcode=2015PNAS..112E.693D |doi-access=free }}</ref><ref name="Adl 2019">{{cite journal|vauthors=Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, Cárdenas P, Čepička I, Chistyakova L, del Campo J, Dunthorn M, Edvardsen B, Eglit Y, Guillou L, Hampl V, Heiss AA, Hoppenrath M, James TY, Karnkowska A, Karpov S, Kim E, Kolisko M, Kudryavtsev A, ((Lahr DJG)), Lara E, Le Gall L, Lynn DH, Mann DG, Massana R, ((Mitchell EAD)), Morrow C, Park JS, Pawlowski JW, Powell MJ, Richter DJ, Rueckert S, Shadwick L, Shimano S, Spiegel FW, Torruella G, Youssef N, Zlatogursky V, Zhang Q|year=2019|title=Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes|journal=Journal of Eukaryotic Microbiology|volume=66|issue=1 |pages=4–119|doi=10.1111/jeu.12691|pmid=30257078 |pmc=6492006 }}</ref>
{{clade|style=font-size:90%;|label1=[[Podiata]]|1={{clade|1=[[CRuMs]] [[File:12862_2018_1224_Fig1i.jpg|60px]]|label2=[[Amorphea]]|2={{clade|1=[[Amoebozoa]] [[File:Amoeba_proteus_with_many_pseudopodia.jpg|60px]]|label2=[[Obazoa]]|2={{clade|1=[[Breviatea]]|barbegin1=blue|2={{clade|1=[[Thecomonadea]] [[File:Podomonas_kaiyoae_C.jpg|60px]]|barend1=blue|label2=[[Opisthokonta]]|2={{clade|1=[[Holozoa]] (includes [[animals]]) [[File:Loligo_vulgaris.jpg|60px]]|2=[[Holomycota]] (includes [[fungi]]) [[File:Boletus_edulis_(Tillegem).jpg|60px]]}}}}}}}}}}
|grouplabel1={{clade labels|label1='''Apusozoa'''|top1=45%}}
}}

==References==
{{Reflist|2}}

==External links==
{{Wikispecies}}
{{Commons category|Apusozoa}}

{{Eukaryota}}
{{Taxonbar|from=Q645245}}

[[Category:Apusozoa| ]]
[[Category:Amorphea phyla]]
[[Category:Taxa named by Thomas Cavalier-Smith]]
[[Category:Obsolete eukaryote taxa]]

{{Unikont-stub}}