Archaea phylogeny
From Palaeos
| Archaea |
| Fossil record | Phylogeny | Characteristics | Ecology | Links | References |
The Archaea are divided by rRNA trees into two major clades, Crenarchaeota and Euryarchaeota.
Recently a third branch has been named, the 'Nanoarchaeota', with a single species, 'Nanoarchaeum equitans' (Huber, Hohn et al., 2002). 'Nanoarchaeum' is a greatly reduced, obligate symbiont of another hyperthermophilic archaeon, Ignicoccus. However, 'Nanoarchaeum' has not yet been validly described under the Bacteriological Code of Nomenclature (which requires, among other things, validation in the International Journal of Systematic and Evolutionary Microbiology and deposition of an isolated culture in at least two repositories). Also, the highly reduced nature of 'Nanoarchaeum' makes it not impossible that it has a spuriously low position on the phylogenetic tree, as has been demonstrated for Microsporidia.
A fourth branch, the 'Korarchaeota', has only been recognised from environmental DNA sequences. No members of this group have yet been recognised as live organisms.
Credits CKT060920
