A Gram-strain-negative, coccoid bacterium, lacking bacteriochlorophyll, designated strain T1lg56T, was isolated from a sediment sample collected from Ximen island mangrove forest, Zhejiang province, China. Cells were halotolerant, and catalase- and oxidase-positive. Growth was observed at 18-42 °C (optimum, 35 °C), at pH 6.0-9.5 (optimum, pH 6.5) and in the presence of 0-15 % (w/v) NaCl (optimum, 2-5 %). The major cellular fatty acids were C18 : 1ω7c and C16 : 0. The polar lipid profile of strain T1lg56T consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylmonomethylethanolamine, two unidentified phospholipids and five unidentified lipids. Ubiquinone-10 was the predominant respiratory quinone. The assimilation of the substrates in the API 20NE kit was positive in strain T1lg56T. The DNA G+C content of strain T1lg56T was 67.2 mol%. 16S rRNA gene sequence analysis indicated that strain T1lg56T was a member of family Rhodobacteraceae and was closely related to Poseidonocella pacifica KMM 9010T, with 95.7 % similarity to the type strain. Phylogenetic analysis showed that strain T1lg56T formed a separate evolutionary branch, and was parallel to other related genera of Rhodobacteraceae. Its phylogenetic distinctiveness and distinguishing phenotypic characteristics supported that strain T1lg56T represents a novel genus of the family Rhodobacteraceae, for which the name Mangrovicoccus ximenensis gen. nov., sp. nov. is proposed. The type strain is T1lg56T (=CCTCC AB 2016238T=KCTC 52623T).