Taxonomic evaluation of the genera Ruegeria and Silicibacter: a proposal to transfer the genus Silicibacter Petursdottir and Kristjansson 1999 to the genus Ruegeria Uchino et al. 1999.

The taxonomic positions of the genera Ruegeria and Silicibacter were evaluated by a polyphasic investigation. It was evident from 16S rRNA gene sequence analysis that both genera are closely related as they formed a monophyletic clade with high sequence similarities (96.9-98.2 %). Several properties commonly found in these taxa strongly suggest that they should be classified in the same genus. Further, a comparative study based on DNA-DNA hybridization, phenotypic characterization and chemotaxonomic analysis indicated that the members of this clade, namely Ruegeria atlantica, Silicibacter lacuscaerulensis and Silicibacter pomeroyi, can be readily differentiated from each other. On the basis of the polyphasic data obtained in this study, all species of the genus Silicibacter should be transferred to the genus Ruegeria, since the latter has nomenclatural priority. It is therefore proposed that Silicibacter lacuscaerulensis and Silicibacter pomeroyi are transferred to the genus Ruegeria as Ruegeria lacuscaerulensis comb. nov. and Ruegeria pomeroyi comb. nov.