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  Tree of Rhizaria
 

 

Rhizaria is a heterogeneous assemblage of protists, which includes the majority of filose and reticulose amoebae and most actinopods, plus two parasitic lineages and some flagellates. The term Rhizaria was proposed by Cavalier-Smith (2002), and refers to the root-like filose and reticulose pseudopodia and/or axopodia characterizing the majority of the taxa included in it. The existence of this supergroup is based exclusively on molecular evidence that accumulated since the demonstration of the close relationship between euglyphid amoebae and chlorarachniophytes (Bhattacharya et al. 1995), and their grouping with cercomonad and thaumatomonad flagellates in SSU rRNA trees (Cavalier-Smith and Chao 1997). The Rhizaria are also supported by analyses of actin (Keeling 2001, Nikolaev et al. 2004), polyubiquitin (Archibald et al. 2003), and RNA polymerase II (Longet et al. 2003) genes. According to the most recent paper (Nikolaev et al. 2004), Rhizaria includes core cercozoans (comprising among others the Euglyphida, Chlorarachniophyta, Phaeodarea, and Desmothoracida), some parasites of plants (Phytomyxea) and animals (Haplosporidia), the Foraminifera, Gromia, and radiolarians (Acantharea + Polycystinea + Taxopodida).

Figure : Maximum likelihood phylogeny of Rhizaria inferred from SSU rRNA gene sequences using the GTR+G+I model of evolution.

 

 





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