A novel actinobacterium, designated strain MSW-19(T), was isolated from a seawater sample in Republic of Korea. Cells were aerobic, Gram-positive, non-endospore-forming, and non-motile cocci. Colonies were circular, convex, opaque, and vivid yellow in colour. A phylogenetic tree based on 16S rRNA gene sequences exhibited that the organism formed a distinct clade within the radius encompassing representatives of the family Propionibacteriaceae. The phylogenetic neighbors were the type strains of the genera Friedmanniella, Microlunatus, Micropruina, Propionicicella, and Propionicimonas. Levels of 16S rRNA gene sequence similarity between the isolate and members of the family were less than 95.3%. The cell wall peptidoglycan of the organism contained LL-diaminopimelic acid as the diagnostic diamino acid. The isolate contained MK-9(H(4)) as the predominant menaquinone, ai-C(15:0) as the major fatty acid and polar lipids including phosphatidylglycerol, phosphatidylethanolamine, and an unknown phospholipid. The G+C content of the DNA was 69.6 mol%. On the basis of the phenotypic and phylogenetic data presented here, the isolate is considered to represent a novel genus and species in the family Propionibacteriaceae, for which the name Ponticoccus gilvus gen. nov., sp. nov. is proposed. The type strain is strain MSW-19(T) (= KCTC 19476(T)= DSM 21351(T)).