dpann 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 parvarchaeum acidiphilum scientific classification domain: archaea superphylum: dpannrinke et al. 2013 phyla aenigmatarchaeota altarchaeota diapherotrites huberarchaeota mamarchaeota micrarchaeota nanoarchaeota nanohalarchaeota pacearchaeota parvarchaeota undinarchaeota woesearchaeota 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. characteristics they are characterized by being small in size compared to other archaea (nanometric size) and in keeping with their small genome, they have limited but sufficient catabolic capacities to lead a free life, although many are episymbionts that depend on a symbiotic or parasitic association with other organisms. many of their characteristics are similar or analogous to those of ultra-small bacteria (cpr group). limited metabolic capacities are a product of the small genome and are reflected in the fact that many lack central biosynthetic pathways for nucleotides, aminoacids, and lipids; hence most dpann archaea, such as arman archaea, which rely on other microbes to meet their biological requirements. but those that have the potential to live freely are fermentative and aerobic heterotrophs. they are mostly anaerobic and cannot be cultivated. they live in extreme environments such as thermophilic, hyperacidophilic, hyperhalophilic or metal-resistant; or also in the temperate environment of marine and lake sediments. they are rarely found on the ground or in the open ocean. classification diapherotrites. found by phylogenetic analysis of the genomes recovered from the groundwater filtration of a gold mine abandoned in the usa. parvarchaeota and micrarchaeota. discovered in 2006 in acidic mine drainage from a us mine. they are of very small size and provisionally called arman (archaeal richmond mine acidophilic nanoorganisms). woesearchaeota and pacearchaeota. they have been identified both in sediments and in surface waters of aquifers and lakes, abounding especially in saline conditions. aenigmarchaeota. found in wastewater from mines and in sediments from hot springs. nanohalarchaeota. distributed in environments with high salinity. nanoarchaeota. they were the first discovered (in 2002) in a hydrothermal source next to the coast of iceland. they live as symbionts of other archaea. phylogeny tom a. williams et al. 2017, castelle et al. 2015 and dombrowski et al. 2020. jordan et al. 2017 cavalier-smith2020 and feng et al 2021. dpann may be the first divergent clade of archaea according to some phylogenetic analyses. recent phylogenetic analyses have found the following phylogeny between phyla. bacteria archaea dpann altarchaeota diapherotrites micrarchaeota undinarchaeota aenigmatarchaeota nanohaloarchaeota nanoarchaeota parvarchaeota mamarchaeota pacearchaeota woesearchaeota euryarchaeota proteoarchaeota tack asgard lokiarchaeota odinarchaeota thorarchaeota heimdallarchaeota (+α─proteobacteria) eukaryota other phylogenetic analyzes have suggested that dpann could belong to euryarchaeota or that it may even be polyphyletic occupying different positions within euryarchaeota. it is also debated whether the phylum altiarchaeota should be classified in dpann or euryarchaeota. an alternative location for dpann in the phylogenetic tree is as follows. the groups marked in quotes are lineages assigned to dpann, but phylogenetically separated from the rest. bacteria archaea euryarchaeota thermococci hadesarchaea methanobacteria methanopyri methanococci thermoplasmata archaeoglobi methanomicrobia "nanohaloarchaeota" haloarchaea "altarchaeota" dpann diapherotrites micrarchaeota undinarchaeota aenigmatarchaeota nanoarchaeota parvarchaeota mamarchaeota pacearchaeota woesearchaeota proteoarchaeota tack asgard lokiarchaeota odinarchaeota thorarchaeota heimdallarchaeota (+α─proteobacteria) eukaryota taxonomy the currently accepted taxonomy is based on the list of prokaryotic names with standing in nomenclature (lpsn) and national center for biotechnology information (ncbi). gtdb phylogeny of "dpann" (fitted to accepted taxonomy) dpann "altarchaeota" "altarchaeia" "altarchaeales" "iainarchaeota" "iainarchaeia" 0-14-0-20-30-16 "iainarchaeales" "micrarchaeota" "micrarchaeia" "norongarragalinales" "micrarchaeales" "burarchaeales" "fermentimicrarchaeales" "gugararchaeales" "anstonellales" "undinarchaeota" "undinarchaeia" "undinarchaeales" "huberarchaeaota" "huberarchaeia" "huberarchaeales" "aenigmarchaeota" "aenigmarchaeia" "aenigmarchaeales" "nanohalarchaeota" "nanohalobiia" "nanohalobiales" "nanoarchaeota" "nanoarchaeia" "nanoarchaeales" "pacearchaeales" "woesearchaeales" "tiddalikarchaeales" "parvarchaeales" super phylum "dpann" rinke et al. 2013 phylum altarchaeota probst et al. 2018 (sm1) class "altarchaeia" corrig. probst et al. 2014 order "altarchaeales" corrig. probst et al. 2014 phylum "iainarchaeota" (dusel-3) class "iainarchaeia" rinke et al. 2020 "candidatus forterrea" probst & banfield 2017 order "iainarchaeales" rinke et al. 2020 phylum "micrarchaeota" baker & dick 2013 class "micrarchaeia" vazquez-campos et al. 2021 order "anstonellales" vazquez-campos et al. 2021 (lfwa-iiic) order "burarchaeales" vazquez-campos et al. 2021 (lfwa-iiib) order "fermentimicrarchaeales" kadnikov et al. 2020 order "gugararchaeales" vazquez-campos et al. 2021 (lfwa-iiia) order "micrarchaeales" vazquez-campos et al. 2021 order "norongarragalinales" vazquez-campos et al. 2021 (lfwa-ii) phylum "undinarchaeota" dombrowski et al. 2020 class "undinarchaeia" dombrowski et al. 2020 order "undinarchaeales" dombrowski et al. 2020 phylum "huberarchaeota" probst et al. 2019 class "huberarchaeia" corrig. probst et al. 2019 order "huberarchaeales" rinke et al. 2020 phylum "aenigmatarchaeota" corrig. rinke et al. 2013 (dseg, dusel2) class "aenigmatarchaeia" corrig. rinke et al. 2020 order "aenigmatarchaeales" corrig. rinke et al. 2020 phylum "nanohalarchaeota" corrig. rinke et al. 2013 class "nanohalobiia" corrig.la cono et al. 2020 order "nanohalobiales" la cono et al. 2020 class ?"nanohalarchaeia" corrig. narasingarao et al. 2012 order "nanohalarchaeales" phylum "nanoarchaeota" huber et al. 2002 class "nanoarchaeia" vazquez-campos et al. 2021 order "nanoarchaeales" huber et al. 2011 order "pacearchaeales" (dhve-5, dusel-1) order "parvarchaeales" rinke et al. 2020 (arman 4 & 5) order "tiddalikarchaeales" vazquez-campos et al. 2021 (lfw-252_1) order "woesearchaeales" (dhve-6) phylum ?"mamarchaeota" order ?"wiannamattarchaeales"