Figure 1.

Phylogenetic tree highlighting the position of S. africana relative to the type strains of the other species within the phylum ‘Spirochaetes’. The tree was inferred from 1,332 aligned characters [7,8] of the 16S rRNA gene sequence under the maximum likelihood (ML) criterion [9]. Rooting was done initially using the midpoint method [10] 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 adjacent to the branches are support values from 350 ML bootstrap replicates [11] (left) and from 1,000 maximum-parsimony bootstrap replicates [12] (right) if larger than 60%. Lineages with type strain genome sequencing projects registered in GOLD [13] are labeled with one asterisk, those also listed as ‘Complete and Published’ with two asterisks (see [14–20] and CP003155 for Sphaerochaeta pleomorpha, CP002903 for Spirochaeta thermophila, CP002696 for Treponema brennaborense, CP001841 for T. azotonutricium and CP001843 for T. primitia. Note: Spirochaeta caldaria, S. stenostrepta and S. zuelzerae were effectively renamed to T. caldaria, T. stenostrepta and T. zuelzerae in [15], however, the names have not yet been validily published.