DPANN

DPANN is a superphylum 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.

DPANN is an acronym formed by the initials of the first five groups discovered, Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota and Nanohaloarchaeota. Later Woesearchaeota and Pacearchaeota were discovered and proposed within the DPANN superphylum. In 2017, another phylum Altiarchaeota was placed into this superphylum. The monophyly of DPANN is not yet considered established, due to the high mutation rate of the included phyla, which can lead to the artifact of the long branch attraction (LBA) where the lineages are grouped basally or artificially at the base of the phylogenetic tree without being related. These analyzes instead suggest that DPANN belongs to Euryarchaeota or is polyphyletic occupying various positions within Euryarchaeota.

The DPANN groups together different phyla with a variety of environmental distribution and metabolism, ranging from symbiotic and thermophilic forms such as Nanoarchaeota, acidophiles like Parvarchaeota and non-extremophiles like Aenigmarchaeota and Diapherotrites. DPANN was also detected in nitrate-rich groundwater, on the water surface but not below, indicating that these taxa are still quite difficult to locate.