A Gram-negative, non-motile, rod-shaped bacterial strain, JLT354-W(T), that accumulates poly-beta-hydroxybutyrate granules was isolated from the South China Sea. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain was related to members of the genera Antarctobacter, Sagittula, Oceanicola and Loktanella; levels of similarity between strain JLT354-W(T) and members of the above genera were less than 92.0 %. The predominant fatty acid of strain JLT354-W(T) was C(18 : 1)omega7c (83.1 %); significant amounts of C(18 : 0) (7.9 %) and C(12 : 1) 3-OH (3.7 %) were also present. The predominant respiratory ubiquinone was Q-10. The DNA G+C content of strain JLT354-W(T) was 63.7 mol%. The isolate was distinguishable from members of the order Rhodobacterales based on phenotypic and biochemical characteristics. On the basis of the taxonomic data presented, strain JLT354-W(T) is considered to represent a novel species of a new genus, for which the name Mameliella alba gen. nov., sp. nov. is proposed. The type strain of Mameliella alba is JLT354-W(T) (=LMG 24665(T)=CGMCC 1.7290(T)).