Monotypic archaea genera

Ignisphaera is a genus of the Desulfurococcales. Ignisphaera aggregans is a coccoid- shaped, fourth type strain that is strictly anaerobes with anaerobic respiration. This archaea species are hyperthermophiles that were found in New Zealand's hot springs in Kuirau Park, Rotorua.

Stetteria is a genus of archaeans in the family Desulfurococcaceae. Up to now there is only one species of this genus known, Stetteria hydrogenophila.

Thermosphaera is a genus of the Desulfurococcaceae. They are a group of prokaryotic organisms which have been discovered in extremely hot environments such as sulfur springs, volcanoes, and magma pools. Isolates of Thermosphaera were first identified in 1998 from the Obsidian Pool in Yellowstone National Park.

Sulfophobococcus is a genus of the Desulfurococcaceae.

Natronolimnobius (common abbreviation Nln.) is a genus of archaeans in the family Natrialbaceae.

Thermodiscus is a genus of archaea in the family Desulfurococcaceae. The only species is Thermodiscus maritimus.

'"Candidatus Sukunaarchaeum mirabile"' (provisional name) is a species of archaea of which only the DNA is known, but which already presents several particularities: it is a holoparasite of the dinoflagellate Citharistes regius and is the first known parasitic archaean. Its DNA, the smallest known for an archaeon, codes for only proteins necessary for reproduction.