Phylogenetic tree highlighting the position of O. splanchnicus relative to the other type strains within the family Porphyromonadaceae. The tree was inferred from 1,401 aligned characters [11,12] of the 16S rRNA gene sequence under the maximum likelihood criterion . Rooting was done initially using the midpoint method  and then checked for its agreement with the current classification (Table 1). The branches are scaled in terms of the expected number of substitutions per site. Numbers to the right of bifurcations are support values from 250 bootstrap replicates  if larger than 60%. Lineages with type strain genome sequencing projects registered in GOLD  are labeled by one asterisk, published genomes by two asterisks [17–19].