TABLE 1.

Validly published named prokaryotes used in the analyses^a

Rank	No. validly published	No. covered (16S)b	No. of genomes	No. of outliers	No. of singletons	No. with taxon sizef of:
						2 or 3	4 to 9	≥10
Species	12,981	11,800	4,092c	274	11,800	0	0	0
Genus	2,716	2,422	1,333	131	1,166	616	437	203
Family	389	451d	343	86	121	71	79	180
Order	174	202d	161	47	52	28	34	90
Class	83	85d	69	19	23	13	14	35
Phylum	0	34e	33	9	4	4	6	20
Domain	0	2	2	2	0	0	0	2

^aAs of 5 December 2015, there were 12,981 validly published named species and subspecies of Bacteria and Archaea.

^bA review of the taxonomic literature yielded 12,481 sequences (16S rRNA) that could be confirmed as derived from type strains, of which 11,800 were considered of sufficient quality to be used in analyses (>1,300 nt, <3% ambiguity); A total of 407 sequences were excluded from the analyses because of quality considerations, and 274 were flagged as outliers during the first pass through the self-organizing self-correcting classifier.

^cAt present, there are 4,733 genome sequences of varying quality and completeness that can be identified with some certainty as derived from type strains. Of these, 641 are replicates that have been sequenced 2 to 10 times and appear in GenBank with a sequence name can be positively associated with a known strain identifier or culture collection accession number for the type strain. Three of the genomes have been sequenced multiple times as synonyms.

^dThere are currently 92 species that have not been placed into families, orders, and/or classes. In these instances, the lower taxa are placed into unnamed, numbered ranked categories designated as Incertae sedis.

^eCurrently, the names of the phyla and domains are not covered by the International Code of Nomenclature of Prokaryotes and cannot be considered validly published.

^fTaxon size is the number of members in the next lower rank. For example, 4 phyla have 2 or 3 classes, 6 phyla have 4 to 9 classes, and 20 phyla have ≥10 classes.