The phylogenetic tree is based on alignment of in frame concatenated DNA sequence fragments from 8 housekeeping genes (clpA, clpX, nifS, pepX, pyrG, recG, rplB, and uvrA) (n = 4,791 bp). Strains sequenced in this study are highlighted as follows: blue, B. burgdorferi; purple, B. mayonii; red, B. miyamotoi; pink, B. hermsii, and orange, Candidatus B. johnsonii. Publicly available sequences for 18 different Bbsl genospecies and 10 different RF borreliae (gray) were included for comparison. The scale bar corresponds to 0.1 substitutions per nucleotide position.