A Gram-reaction-negative, proteorhodopsin-containing, yellow-pigmented, rod-shaped, non-gliding and strictly aerobic bacterium, designated strain YIK12(T), was isolated from tidal flat sediment of Yeongheung Island at the coast of the West Sea of Korea. Cells produced non-diffusible carotenoid pigments, but not flexirubin-type pigment. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the isolate was affiliated to the family Flavobacteriaceae and showed highest similarity to Sediminibacter furfurosus MAOS-86(T) (93.3%). Growth was observed at 24-44 °C (optimum 30 °C), at pH 6.5-8.0 (optimum 7.0) and in the presence of 1.5-7.0% sea salts (optimum 2%). The DNA G+C content was 40.4 mol% and the predominant cellular fatty acids were iso-C(15 : 0), iso-C(15 : 1) G, iso-C(17 : 0) 3-OH, iso-C(16 : 0) 3-OH, anteiso-C(15 : 0) and iso-C(15 : 0) 3-OH. The major respiratory quinone was MK-6. On the basis of data from the present polyphasic taxonomic study, strain YIK12(T) is considered to represent a novel species of a new genus in the family Flavobacteriaceae, for which the name Hoppeia youngheungensis gen. nov., sp. nov. is proposed. The type strain of H. youngheungensis is YIK12(T) ( = KCCM 43023(T) = JCM 19488(T)). Emended descriptions of the genus Sediminibacter and Sediminibacter furfurosus are given.