Phylogenetic analysis using the neighbor-joining method based on 16S rRNA gene sequences of representative Williamsia species showing the position of the S and R morphotypes of isolate IMMIB W-9660. The numbers at the nodes indicate the level of bootstrap support of >70% based on analyses of 1,000 resampled data sets. Bar, 1.0% sequence divergence. Arcanobacterium haemolyticum was used as an outgroup.