kryptonia kryptonia kryptonia is a bacterial phylum with candidate status. it is a member of the fcb group. kryptonia scientific classification domain: bacteria superphylum: fcb group phylum: kryptoniacastelle et al. 2013 class: "kryptonia" order: "kryptoniales" family: "kryptoniaceae" genera "ca. chrysopegocella" "ca. kryptobacter" "ca. kryptonium" "ca. thermokryptus" the phylum was first proposed in 2016 following the recovery of genomes from a large-scale effort to mine metagenomic and single-cell genomic datasets for novel bacterial diversity. extensive analysis of 5.2 tb of metagenomic data from around the world suggests members of kryptonia are found exclusively in high-temperature ph-netural geothermal springs, such as the jinze pool (yunnan province, china), dewar creek spring (british columbia, canada), and great boiling spring (nevada, usa). due to primer mismatches, members of this phylum have been widely under-detected in 16s rrna sequencing-based surveys of community composition. analysis of the first genomes recovered from this group (from four different genera) suggests that members of kryptonia are heterotrophs with a putative capacity for iron respiration. they are inferred to be incapable of some producing key metabolic compounds on their own (e.g.: biotin, certain amino acids), and thus may be metabolically dependent on other microbes in their environment, although the nature of such a relationship is unknown. the name "kryptonia" is derived from the greek work "krupton", which means "hidden" or "secret". this is a nod to the phylum having hitherto eluded detection due to ssu rrna primer biases. 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). phylogeny of "kryptonia" "ca. kryptonium" "ca. k. mobilis" "ca. k. kryptomonas" "ca. k. tengchongensis" "ca. k. thompsoni" class "kryptonia" order "kryptoniales" family "kryptoniaceae" genus "ca. chrysopegocella" eloe-fadrosh et al. 2016 corrig. oren et al. 2020 "ca. chrysopegocella kryptomonas" eloe-fadrosh et al. 2016 corrig. oren et al. 2020 genus "ca. kryptobacter" eloe-fadrosh et al. 2016 "ca. kryptobacter tengchongensis" eloe-fadrosh et al. 2016 genus "ca. kryptonium" eloe-fadrosh et al. 2016 "ca. kryptonium thompsoni" eloe-fadrosh et al. 2016 genus "ca. thermokryptus" eloe-fadrosh et al. 2016 "ca. thermokryptus mobilis" eloe-fadrosh et al. 2016