Cercomonadida

Cercomonads
Cercomonas sp
Scientific classification
Domain:	Eukaryota
(unranked):	SAR
(unranked):	Rhizaria
Phylum:	Cercozoa
Class:	Sarcomonadea
Order:	Cercomonadida Poche, 1913
Genera
Cercomonadidae    Cercomonas    Helkesimastix Heteromitidae    Heteromita    Protaspis    Allantion    Sainouron    Cholamonas    Katabia

Cercomonads are small flagellates,^[1] widespread in aqueous habitats and common in soils.^[2]

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,^[3] 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,^[4] 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, and some have been moved to other groups.

References

1. Mylnikov, A.P.; Karpov, S.A. (2004). "Review of diversity and taxonomy of cercomonads" (PDF). Protistology. 3 (4): 201–217.
2. 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. PMID 16647880.
3. 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. PMID 19589724.
4. Bass D, Richards TA, Matthai L, Marsh V, Cavalier-Smith T (2007). "DNA evidence for global dispersal and probable endemicity of protozoa". BMC Evol. Biol. 7: 162. doi:10.1186/1471-2148-7-162. PMC 2194784. PMID 17854485.