Fig 1. Unrooted phylogeny of bacteria built with concatenated ribosomal protein sequences, following [22] with additional data from newly described phototrophs in the phylum Eremiobacterota (here labeled by their alternate name WPS2) [21,23] and the Chloroflexi class Anaerolineae [19].

Occurrences of reaction center-based phototrophy within a phylum indicated by shading of the entire phylum, color coded by reaction center type (RC1 for Type 1 anoxygenic reactions centers, RC2 for Type 2 anoxygenic reaction centers, PSI for photosystem 1, PSII for photosystem 2). For clarity, the entire phylum is highlighted even when phototrophy is restricted to only some members (e.g. the phototrophic Heliobacteria within the much broader, predominantly nonphototrophic, Firmicutes phylum).