Cercomonad

{{Short description|Order of single-celled organisms}} {{Automatic taxobox | name = Cercomonads | image = Cercomonas sp.jpg | image_caption = ''Cercomonas'' sp | taxon = Cercomonadida | authority = Poche, 1913 emend. Cavalier-Smith, 2012 | subdivision_ranks = Genera | subdivision = *'''Cavernomonadidae''' ** ''Cavernomonas'' *'''Cercomonadidae''' ** ''Cercomonas'' ** ''Eocercomonas'' ** ''Filomonas'' ** ''Neocercomonas'' | synonyms_ref = <ref name="Adl 2019">{{cite Q|Q57086550}}</ref> | synonyms = {{center|Cercobodonidae {{au|Hollande 1942}}}} }}

'''Cercomonads''' are small amoeboflagellates,<ref name="Mylnikov 2004">{{cite Q|Q124459772}}</ref> widespread in aqueous habitats and common in soils.<ref name="pmid16647880">{{cite journal |vauthors=Karpov SA, Bass D, Mylnikov AP, Cavalier-Smith T |title=Molecular phylogeny of Cercomonadidae and kinetid patterns of Cercomonas and Eocercomonas gen. nov. (Cercomonadida, Cercozoa) |journal=Protist |volume=157 |issue=2 |pages=125–58 |date=June 2006 |pmid=16647880 |doi=10.1016/j.protis.2006.01.001 }}</ref>

==Characteristics== The cells are generally around 10 μm in length, without any shell or covering. They produce filose pseudopods to capture bacteria, but do not use them for locomotion, which usually takes place by gliding along surfaces.

Most members have two flagella,<ref>{{Cite journal | last1 = Bass | first1 = D. | last2 = Howe | first2 = A. | last3 = Mylnikov | first3 = A. | last4 = Vickerman | first4 = K. | last5 = Chao | first5 = E. | last6 = Edwards Smallbone | first6 = J. | last7 = Snell | first7 = J. | last8 = Cabral Jr | first8 = J. | last9 = Cavalier-Smith | first9 = T. | title = Phylogeny and Classification of Cercomonadida (Protozoa, Cercozoa): Cercomonas, Eocercomonas, Paracercomonas, and Cavernomonas gen. Nov | journal = Protist | volume = 160 | issue = 4 | pages = 483–521 | year = 2009 | pmid = 19589724 | doi = 10.1016/j.protis.2009.01.004 }}</ref> one directed forward and one trailing under the cell, inserted at right angles near its anterior. The nucleus is connected to the flagellar bases and accompanied by a characteristic paranuclear body.

[[File:2023_Cercomonad.svg|center|thumb|upright=2|{{center|'''Representation of a cercomonad'''}}{{ordered list|Anterior flagellum| Microtubular bands| Fibrillar rootlet| Golgi apparatus; modifies proteins and sends them out of the cell| Microtubule cone| Nucleus| Nucleolus| Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell| Extrusome| Contractile vacuole, regulates the quantity of water inside a cell| Dense granule| Mitochondrion, creates ATP (energy) for the cell, tubular cristae| Food vacuole| Prey (bacteria)| Lysosome, holds enzymes| Posterior flagellum}}]]

==Classification==

Genetic studies place the cercomonads among the Cercozoa,<ref name="pmid17854485">{{cite journal |vauthors=Bass D, Richards TA, Matthai L, Marsh V, Cavalier-Smith T |title=DNA evidence for global dispersal and probable endemicity of protozoa |journal=BMC Evol. Biol. |volume=7 |pages=162 |year=2007 |pmid=17854485 |pmc=2194784 |doi=10.1186/1471-2148-7-162 |doi-access=free }}</ref> a diverse group of amoeboid and flagellate protozoans. They are divided into two families. * The Heteromitidae tend to be relatively rigid, and produce only temporary pseudopods. * The Cercomonadidae are more plastic, and when food supplies are plentiful may become amoeboid and even multinucleate.

The classification of genera and species continues to undergo revision. Some genera have been merged, like ''Cercomonas'' and ''Cercobodo''. Others like ''Helkesimastix'', ''Sainouron'' and ''Cholamonas'' have been moved to Helkesida,<ref>{{cite journal |last=Cavalier-Smith |first=T. |title=Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences |journal=Protoplasma |volume=255 |issue=1 |pages=297–357 |year=2018 |pmc=5756292 |doi=10.1007/s00709-017-1147-3 |pmid=28875267}}</ref> while the rest of the family Heteromitidae has been moved to Glissomonadida.<ref>{{cite journal |last1=Howe |first1=A. T. |last2=Bass |first2=D. |last3=Vickerman |first3=K. |last4=Chao |first4=E. E. |last5=Cavalier-Smith |first5=T. |title=Phylogeny, taxonomy, and astounding genetic diversity of Glissomonadida ord. nov., the dominant gliding zooflagellates in soil (Protozoa: Cercozoa) |journal=Protist |volume=160 |issue=2 |pages=159–189 |year=2009 |doi=10.1016/j.protis.2008.11.007 |pmid=19324594}}</ref>

* ''Cavernomonas'' Vickerman 2009 * ''Cercomonas'' Dujardin 1841 emend. Karpov et al. 2006 non emend. Ekelund et al. 2004 [''Cercobodo'' Krassilstschick 1886; ''Cercomastix'' Lemmermann 1913; ''Dimastigamoeba'' Blochmann 1894; ?''Mukdeniamonas'' Skwortzov 1960; ?''Changia'' Skwortzov 1960 non Sun 1924; ?''Reptomonas'' Kent 1880; ''Dimorpha'' Klebs 1892 non Gruber 1882] * ''Eocercomonas'' Karpov et al. 2006 * ''Filomonas'' Cavalier-Smith & Karpov 2012 * ''Neocercomonas'' Ekelund, Daugbjerg & Fredslund 2004

==References== {{Reflist}}

Category:Cercomonadida Category:Cercozoa