Phylogenetic tree showing relationship between A2, B1, B6, D7, E1, F8, and C2 species (shown on tree with arrows) and other Helicobacter and related species. The scale represents a 1% difference in nucleotide sequence. Vertical distance has no meaning. The tree was rooted with Wolinella succinogenes and Campylobacter jejuni as outgroups. ∗, formerly known as G. hominis type 1; ∗∗, formerly known as G. hominis type 2.