Proposal of Cobetia marina gen. nov., comb. nov., within the family Halomonadaceae, to include the species Halomonas marina

Abstract

At present the family Halomonadaceae consists of four genera and the taxonomic status of all species included in these genera is not equally supported by phylogenetic evidence. Whereas Zymobacter and Carnimonas contain one single species each and form the deeper branch of the family, the genus Halomonas contains currently 22 species, with a maximum 16S/23S rRNA sequence divergence greater than it could be expected for species of the same genus. In addition, we have witnessed during last years an increase in the number of new species within this group, which makes even more necessary a taxonomic rearrangement. In a previous study (Arahal et al., 2002) we evaluated the phylogenetic status of the family Halomonadaceae based on 23S and 16S rDNA sequence analyses and mentioned that Halomonas marina could eventually be assigned to a new genus. In this study we have emended the description of this species, including new features and propose its placement in a new genus, Cobetia gen. nov. within the family Halomonadaceae. The type strain of Cobetia marina is ATCC 25374T (= DSM 4741T). Further discussion on the phylogeny of the family Halomonadaceae is provided taking into account the most recent changes.