prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Bacteria" Woese et al. 1990
     Phylum "Verrucomicrobia" Hedlund 2011
       1 Class "Spartobacteria" Sangwan et al. 2004 [monotypic]
       2 Class Opitutae Choo et al. 2007
       3 Class Verrucomicrobiae Hedlund et al. 1998 [monotypic]