Procaryotic Genera Domain "Bacteria" Woese et al. 1990 Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005 Class "Gammaproteobacteria" nom. inval. see Class Gammaproteobacteria Garrity et al. 2005 Order "Xanthomonadales" [monotypic] see Order Xanthomonadales Saddler and Bradbury 2005 Family "Xanthomonadaceae" see Family Xanthomonadaceae Saddler and Bradbury 2005 Genus Xylella Wells et al. 1987