Cercomonadida

Cercomonas sp.

The Cercomonadida are an order of heterotrophic flagellates and assigned to the Cercozoa.

Features

The Cercomonadida are free-living Amöboflagellaten: at least some of the species alternate between amoeboid and flagellate form. A cell wall do not make it. They have two different beating flagella that do not carry Mastigonemata. The anterior flagellum is facing forward and performs percussive movements. The rear scourge runs on the ventral side of the cell along the rear. The occurring at several representatives pseudopodia serve food intake, not like many other amoebas locomotion. Most species are relatively small with around 10 microns.

Some species have a complex life cycle, in which multinucleated and vielgeißelige plasmodia occur. Some species also form cysts. The kinetosomes are connected to the cell nucleus. The mitochondria have tubular cristae. You have Micro bodysuits and various forms of Extrusomen.

Distribution and habitats

The Cercomonadida are distributed worldwide. They are found in marine, brackish and fresh water, even in anoxic habitats such as sewage treatment plants. They also occur on the microbial mats around stromatolites. The genera Cercomonas, Heteromita and Allantion are very widespread in soils and constitute up to half of the total protozoan biomass in the soil. The Cercomonadida Often overlooked, however, due to their small size.

System

The Cercomonadida established by Poche in 1913, replaced the Rhizomastigina of Biitschli and contained only the genus Cercomonas. K. Vickerman has the diagnosis in 1983 expanded to the order now Heteromita included. A further revision of the diagnosis was made in 1986 by Mylnikov. Long the membership of the genera Cercomonas, Heteromita, Bodomorpha, Helkesimastix and Massisteria to order was no disputing the redescription of some species and molecular biological findings led to some changes. Mylnikov and Karpov (2004 ) found in their review the following system, which essentially also by Adl et al. Was acquired in 2005:

• Family Cercomonadidae: the representatives have a variable body shape habitual form pseudopodia, microtubules form a cone and have the Extrusomen Mikrotoxizysten, Trichozysten -like structures and osmiophilic bodies. Some forms form plasmodia.
• Family Heteromitidae: the representatives have a fixed body shape, form a limited time pseudopodia. Microtubule- cone and pseudopodia are missing. As Extrusomen Kinetozysten be formed.

Proleptomonas and Mallisteria are no longer provided to the Cercomonadida but incertae sedis assigned as the next higher taxon Cercozoa. Bodomorpha was incorporated into Cercomonas.

The two families are separated in cladistic analyzes. The sister group of the Cercomonadida likely to be the Silicofilosea.

Documents

• Sina M. Adl et al.: The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists. In: The Journal of Eukaryotic Microbiology. Vol 52, No. 5, 2005 ISSN 1066-5234, pp. 399-451, abstract and full-text.
• Alexander P. Myl'nikov, Serguei A. Karpov: Review of diversity and taxonomy of cercomonads. In: Protistology. Vol 3, No. 4, 2004, ISSN 1680-0826, pp. 201-217, online ( PDF, 249 KB).