Leifsonia poae gen. nov., sp nov., isolated from nematode galls on Poa annua, and reclassification of 'Corynebacterium aquaticum' Leifson 1962 as Leifsonia aquatica (ex Leifson 1962) gen. nov., nom. rev., comb. nov and Clavibacter xyli Davis et al. 1984 with two subspecies as Leifsonia xyli (Davis et al. 1984) gen. nov., comb. nov.

The new genus Leifsonia gen. nov. with two new species, Leifsonia poae sp. nov. (type strain VKM Ac-1401(T)) and Leifsonia aquatica (ex Leifson 1962) nom. rev., comb. nov. (the type species, with VKM Ac-1400(T) = DSM 20146(T) = JCM 1368(T) as type strain), is proposed to accommodate bacteria found i n Poa annua root gall, induced by the nematode Subanguina radicicola, and ' Corynebacterium aquaticum' Leifson 1962. Further, it is proposed to reclass ify Clavibacter xyli Davis et al. 1984 with two subspecies in the new genus as Leifsonia xyli (Davis et al. 1984) comb. nov., Leifsonia xyli subsp, xy li (Davis ef al. 1984) comb. nov. and Leifsonia xyli subsp. cynodontis (Dav is et al. 1984) comb. nov. Members of the proposed genus are characterized by coryneform morphology, peptidoglycans based upon 2,4-diaminobutyric acid , the major menaquinone MK-11, phosphatidylglycerol and diphosphatidylglyce rol as principal phospholipids, the high content of anteiso- and iso-branch ed saturated fatty acids, and a DNA G+C base composition of 66-73 mol%. The y form a distinct phylogenetic branch attached to the line of: descent of A gromyces spp. The new and reclassified species of the new genus clearly dif fer from each other phylogenetically and phenetically and can be recognized by their morphologies, the cell wall sugar composition, the requirement of complex media for growth, and numerous physiological characteristics, incl uding the oxidase reaction.