 Conserved signature indels (CSIs) have also been found specific for the Planctomycetes, Verrucomicrobia, and Chlamydiae that distinguish each respective phylum from one another, and from other bacteria.A three-amino-acid insert in the RNA polymerase protein RpoB has been found that is shared by all sequenced Verrucomicrobia, Chlamydiae, and Lentisphaerae species.The CSI is absent from neighbouring Planctomycetes' and Poribacteria, suggesting common ancestry among the groups for which the CSI is specific.