Proposal of Sphingomonas suberifaciens (van Bruggen, Jochimsen and Brown 1990) Comb. Nov., Sphingomonas natatoria (Sly 1985) Comb. Nov., Sphingomonas ursincola (Yurkov et al. 1997) Comb. Nov., and Emendation of the Genus Sphingomonas