Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990
     Phylum Actinobacteria Garrity and Holt 2001 [monotypic]
       Class Actinobacteria Stackebrandt et al. 1997
         Subclass Actinobacteridae Stackebrandt et al. 1997 see Class Actinobacteria Stackebrandt et al. 1997
           Order Actinomycetales Buchanan 1917 (Approved Lists 1980)
             Suborder Corynebacterineae Stackebrandt et al. 1997
               Family "Williamsiaceae" [monotypic] see Family Nocardiaceae Castellani and Chalmers 1919 (Approved Lists 1980)
                 Genus Williamsia Kämpfer et al. 1999