Archaea kingdoms

Thermoproteati is a kingdom of archaea. Its synonym, "TACK", is an acronym for "Thaumarchaeota" (now Nitrososphaerota), "Aigarchaeota", "Crenarchaeota (now Thermoproteota), and "Korarchaeota", the first groups discovered. They are found in different environments ranging from acidophilic thermophiles to mesophiles and psychrophiles and with different types of metabolism, predominantly anaerobic and chemosynthetic. Thermoproteati is a kingdom that is sister to the "Asgard" branch that gave rise to the eukaryotes. It has been proposed that the Thermoproteati kingdom be classified as "Crenarchaeot

Methanobacteriati (formerly "Euryarchaeota", from Ancient Greek εὐρύς eurús, "broad, wide") is a kingdom of archaea. Methanobacteriati are highly diverse and include methanogens, which produce methane and are often found in intestines; halobacteria, which survive extreme concentrations of salt; and some extremely thermophilic aerobes and anaerobes, which generally live at temperatures between 41 and 122 °C. They are separated from the other archaeans based mainly on rRNA sequences and their unique DNA polymerase. The only validly published name for this group under the Prokaryotic Code is

Nanobdellati (syn. "DPANN") is a kingdom of archaea first proposed in 2013. Many members show novel signs of horizontal gene transfer from other domains of life. They are known as nanoarchaea or ultra-small archaea due to their smaller size (nanometric) compared to other archaea.