Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies [crown] 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] Order Spirochaetalesᵀ Buchanan 1917 (Approved Lists 1980), sedis mutabilis [Family "Brachyspiraceae" nom. ined.] see Family Brachyspiraceae Paster 2012 [Genus Serpula Stanton et al. 1991] see Genus Serpulina Stanton 1992 [Serpula hyodysenteriae (Harris et al. 1972) Stanton et al. 1991] see Brachyspira hyodysenteriae (Harris et al. 1972) Ochiai et al. 1998