A Gram-staining-negative, rod-shaped marine bacterium, designated strain NH57N(T), isolated from sandy sediment in the Mischief Reef of the South China Sea, was characterized based on its physiological and biochemical features, fatty acid profile and phylogenetic position. 16S rRNA gene sequence analysis revealed a clear affiliation with the family Flavobacteriaceae. Strain NH57N(T) showed the closest phylogenetic relationship with members of the genera Gaetbulibacter, Gelidibacter, Subsaxibacter, Subsaximicrobium and Yeosuana; levels of 16S rRNA gene sequence similarity between strain NH57N(T) and the type strains of related species ranged from 94.9 to 91.2 %. Cells of strain NH57N(T) were motile by gliding and grew on solid media as yellow colonies at 9-37 degrees C, pH 6.5-8.5 and in the presence of 0.5-4.0 % NaCl. The DNA G+C content was 32.7 mol% and the predominant fatty acids were iso-C(15 : 1) (22.7 % of the total), iso-C(15 : 0) (20.7 %), iso-C(17 : 0) 3-OH (9.5 %), iso-C(16 : 0) 3-OH (8.3 %), C(15 : 0) (7.8 %) and iso-C(15 : 0) 3-OH (5.8 %). Based on the physiological and phylogenetic data, and on the fatty acid composition, strain NH57N(T) is considered to represent a novel species of a new genus in the family Flavobacteriaceae, for which the name Meridianimaribacter flavus gen. nov., sp. nov. is proposed. The type strain of Meridianimaribacter flavus is NH57N(T) (=CCTCC AB 208318(T)=LMG 24839(T)=MCCC 1A03544(T)).