Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 1990 [paraphyletic?]
             Phylum "Spirochaetes" Garrity and Holt 2001 [monotypic]
               Class Spirochaetesᵀ Cavalier-Smith 2002 [monotypic]
                 1 Order Spirochaetalesᵀ Buchanan 1917 (Approved Lists 1980), sedis mutabilis
                 2 Order Brevinematales Gupta et al. 2014, sedis mutabilis [monotypic]
                 3 Order Brachyspirales Gupta et al. 2014, sedis mutabilis [monotypic]
                 4 Order Leptospirales Gupta et al. 2014, sedis mutabilis [monotypic]