Cercomonads are small
amoeboflagellates,[1] widespread in aqueous habitats and common in soils.[3]
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,[4] 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.
Classification
Genetic studies place the cercomonads among the
Cercozoa,[5] 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 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,[6] while the rest of the family
Heteromitidae has been moved to
Glissomonadida.[7] Most recently, the family
Paracercomonadidae, previously included in this order, has been separated into its own order
Paracercomonadida. This change has made Cercomonadidae the only existing family of cercomonads.[2][8]
^Karpov SA, Bass D, Mylnikov AP, Cavalier-Smith T (June 2006). "Molecular phylogeny of Cercomonadidae and kinetid patterns of Cercomonas and Eocercomonas gen. nov. (Cercomonadida, Cercozoa)". Protist. 157 (2): 125–58.
doi:
10.1016/j.protis.2006.01.001.
PMID16647880.
^Bass, D.; Howe, A.; Mylnikov, A.; Vickerman, K.; Chao, E.; Edwards Smallbone, J.; Snell, J.; Cabral Jr, J.; Cavalier-Smith, T. (2009). "Phylogeny and Classification of Cercomonadida (Protozoa, Cercozoa): Cercomonas, Eocercomonas, Paracercomonas, and Cavernomonas gen. Nov". Protist. 160 (4): 483–521.
doi:
10.1016/j.protis.2009.01.004.
PMID19589724.