A novel marine bacterium was isolated from a sediment sample from Hwasun Beach in Jeju, Republic of Korea. The cells were found to be Gram-negative, aerobic, oxidase-positive, catalase-positive, motile rods. The organism required natural seawater or artificial sea salts for growth. The temperature and pH ranges for growth were 20-42 degrees C and pH 5.1-12.1, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that the organism belonged to the order Rhizobiales and formed a robust cluster with members of the genus Devosia. Its phylogenetic neighbours were the type strains of Devosia riboflavina (96.8 % 16S rRNA gene sequence similarity), Devosia neptuniae (96.7 %), Devosia soli (96.5 %) and Devosia limi (96.2 %), 'Devosia terrae' DCY11 (96.2 %) and 'Candidatus Devosia euplotis' (96.2 %). The predominant ubiquinone was Q-10, the major fatty acids were C(18 : 1), C(18 : 0) and C(16 : 0) and the G+C content of the DNA was 59.1 mol%. On the basis of phenotypic data and the results of phylogenetic analyses, strain HST3-14(T) represents a novel species of the genus Devosia, for which the name Devosia subaequoris sp. nov. is proposed. The type strain is strain HST3-14(T) (=KCTC 12772(T) =JCM 14206(T)).