Bovine digital dermatitis (BDD) is a debilitating infection that is being increasingly recognized in livestock worldwide. Several treponeme phylotypes have been identified in BDD lesions, although only a single BDD-associated treponeme taxon (Treponema brennaborense) has been proposed thus far. In a previous study, we observed that four BDD-associated spirochaete isolates formed a distinct phylogenetic cluster on the basis of 16S rRNA gene sequence analysis and shared less than 97 % sequence similarity with recognized treponeme species. Further characterization of these isolates on the basis of growth characteristics, flaB2 gene sequences, enzyme profiles and cell morphology confirmed that they formed a coherent taxonomic group displaying marked genotypic and phenotypic differences with respect to recognized treponeme species. The four novel isolates displayed a novel 3 : 6 : 3 flagellar pattern rather than the 2 : 4 : 2 pattern shown by their closest relatives and exhibited esterase C4, esterase lipase C8, trypsin and chymotrypsin enzyme activities. Therefore these four new isolates represent a novel species of the genus Treponema, for which the name Treponema pedis sp. nov. is proposed. The type strain is T3552B T (5DSM 18691 T 5NCTC 13403 T ).Treponemes are typically found in the oral cavity, digestive tract and genital areas of humans and animals (Smibert, 1984). Several treponeme taxa are associated with disease and there is an unequivocal aetiology for certain treponeme infections such as human syphilis and yaws, which are caused by Treponema pallidum subsp. pallidum and T. pallidum subsp. pertenue, respectively (Radolf et al., 2006). In contrast, other treponeme infections, such as human periodontal infections and bovine digital dermatitis (BDD), appear to have a more complicated aetiology involving co-infection by several different treponemes (Choi et al., 1997;Dewhirst et al., 2000). Cloning and sequencing of 16S rRNA genes has been used to identify the presence of a diverse range of treponemes in polytreponemally infected tissue, but their highly fastidious nature has, for the most part, precluded any further characterization of these organisms. Although some progress has been made in elucidating the taxonomy of treponemes associated with human periodontal infections, only a single BDD-associated treponeme taxon, Treponema brennaborense (Schrank et al., 1999), has been proposed thus far. This is despite at least five treponeme phylotypes having been identified in BDD lesions (Choi et al., 1997) and several isolation reports of BDD treponemes that correspond to three of the five groups (Evans et al., 2008;Trott et al., 2003;Walker et al., 1995). Furthermore, T. brennaborense was not identified in any BDD lesions during a recent epidemiological study, suggesting that this species may not be as important in disease pathogenesis as initially perceived (Nordhoff et al., 2008).Abbreviations: BDD, bovine digital dermatitis; FCS, fetal calf serum.3Present address: