Taxonomy of Archaea domain

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This is a taxonomic list of domain Archaea.
Halobacterium sp.

Archaea is a domain of prokaryotes, single-celled, chemolithotrophies and extremophiles microorganims. This list show the taxonomy at genus level, based on Garrity et al. (2007) [1] and Euzéby (2008).[2]


Taxonomic notes

Two other possible phyla are described in the literature, Korarchaeota and Nanoarchaeota, meantime its validities are questioned, not being in the last publication of the "Bergey's Manual of Systematic Biology" (2004/05). In 2008, a new phylum was proposed, Thaumarchaeota, to shelter mesophiles archeans.

Known only from gene sequences of rRNA 16S obtained from samples of high temperature hydrothermal fountains of the Yellowstone National Park. Analysis of the material suggests that does not belong to other principal groups of archeans, Crenarchaeota and Euryarchaeota, being of more ancient origin. Meantime, it is possible that the Korarchaeota is not a separate group, but simply an organism that have undergone rapid or unusual mutations of the gene rRNA 16S. [3] [4]

Phylum created in 2002 to harbour a new nanosized hyperthermophilic archaeon from a submarine hot vent, Nanoarchaeum equitans, which relationships are uncertain. rRNA sequence comparisons with the others two phyla, reveals great difference between them. Other investigators, however, suggest that this archaea is related to Thermococcales, a order of the phylum Euryarchaeota. [5] [6] [7]

This phylum was newly-proposed based on phylogenetic data, like sequence of rRNA and the presence of a form of type I topoisomerase, that was previously thought to be unique to the eukaryotes. It harbour mesophilic archeans, what up to that time were grouped in the phylum Crenarchaeota. [8] [9] It contains two orders:[a]


^ These taxa are included in category “Candidatus”, that is not covered by the Rules of the Bacteriological Code. Consequently, the names included in this category cannot be validly published. [10]


  1. GARRITY, G. M.; LILBURN, T. G.; COLE, J. R., HARRISON, S. H.; EUZÉBY, J.; TINDALL, B. J. Part 1 Archaea. In Taxonomic Outline of the Bacteria and Archaeae (TOBA). Version 7.7 2007-4-6. Retrieved 2008-11-20.
  2. EUZÉBY, J. P. Classification of domains and phyla - Hierarchical classification of prokaryotes (bacteria). In List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2008-11-20.
  3. AUCHTUNG, T. A.; TAKACS-VESBACH, C. D.; CAVANAUGH, C. M. (2006). 16S rRNA Phylogenetic Investigation of the Candidate Division “Korarchaeota”. Appl. Environ. Microbiol. 72 (7): 5077–5082. Abstract
  4. BARNS, S. M.; DELWICHE, C. F.; PALMER, J. D.; PACE, N. R. (1996). Perspectives on archaeal diversity, thermophily and monophyly from environmental rRNA sequences. PNAS 93 (17): 9188-9193. Abstract
  5. HUBER, H.; HOHN, M. J.; RACHEL, R.; FUCHS, T.; WIMMER, V.C.; STETTER, K. O. (2002). A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont. Nature 417 (6884): 27 – 8. Abstract
  6. WATERS, E. et al. (2003). The genome of Nanoarchaeum equitans: insights into early archaeal evolution and derived parasitism. Proceedings of the National Academy of Sciences 100 (22): 12984-8. Abstract
  7. BROCHIER, C.; GRIBALDO, S.; ZIVANOVIC, Y.; CONFALONIERI, F.; FORTERRE, P. (2005). Nanoarchaea: representatives of a novel archaeal phylum or a fast-evolving euryarchaeal lineage related to Thermococcales?. Genome Biology 6 (5): R42. Abstract
  8. BROCHIER-ARMANET, C.; BOUSSAU, B.; GRIBALDO, S.; FORTERRE, P. (2008). Mesophilic Crenarchaeota: proposal for a third archaeal phylum, the Thaumarchaeota. Nature Review Microbiology 6 (3): 245-253. Abstract
  9. BROCHIER-ARMANET, C.; GRIBALDO, S.; FORTERRE, P. (2008). A DNA topoisomerase IB in Thaumarchaeota testifies for the presence of this enzyme in the last common ancestor of Archaea and Eucarya. Biology Direct 3: 54. Complet Abstract
  10. EUZÉBY, J. P. Names included in the category Candidatus (Taxonomic category not covered by the Rules of the Bacteriological Code). In List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2009-4-02.