Domain Bacteria Woese et al. 1990
   Phylum Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980)
     Class "Clostridia" Garrity et al. 2001 nom. ined. see Class Clostridia Rainey 2010
       Order Clostridiales Prévot 1953 (Approved Lists 1980)
         Family Syntrophomonadaceae Zhao et al. 1993
           Genus Acetogenium Leigh and Wolfe 1983 see Genus Thermoanaerobacterium Lee et al. 1993
           Genus Aminobacterium Baena et al. 1999
           Genus Aminomonas Baena et al. 1999
           Genus Anaerobaculum Rees et al. 1997
           Genus Anaerobranca Engle et al. 1995
           Genus Caldicellulosiruptor Rainey et al. 1995
           Genus Dethiosulfovibrio Magot et al. 1997
           Genus Syntrophospora Zhao et al. 1990 see Genus Syntrophomonas McInerney et al. 1982
           Genus Thermaerobacter Takai et al. 1999
           Genus Thermanaerovibrio Baena et al. 1999
           Genus Thermohydrogenium Zacharova et al. 1996
           Genus Thermosyntropha Svetlitshnyi et al. 1996
           1 Genus Syntrophomonas McInerney et al. 1982