Bayesian phylogenetic analysis of ribotype sequences from Oceanospirillales bacteria associated with Osedax bone worms (black font) and environmental samples (red font). The yellow highlighted branches include sequences that are new to this study. Closely related endosymbiont ribotypes with genetic distances ≤ 3% were assembled into triangles and designated as ribospecies Rs1–Rs7. For reference, the phylotype designations of Goffredi et al. (P1–P6) and Verna et al. (A–H) are nested within the new ribospecies designations. Groupings of recovered ribotypes that did not cluster with endosymbiont lineages are indicated as Grp1-Grp3). The numbers along branches represent Bayesian posterior probability distributions (PPDs). The branches with PPDs <0.94 were collapsed into polytomies (e.g., M. jannaschi and M. rhizophilum).