A novel Gram-stain-negative, whitish-yellow, rod-shaped, non-pigmented, aerobic, oxidase-positive and catalase-positive bacterium, designated PX7T, was isolated from coastal sediment of Xiaoshi Island, Weihai, China (37° 31' 36″ N, 122° 00' 58″ E). Strain PX7T grew optimally at 30 °C, at pH 7.0-7.5 and in the presence of 3.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain PX7T formed a robust clade with members of the genus Primorskyibacter and was closely related to Primorskyibacter sedentarius, Primorskyibacter aestuariivivens and Primorskyibacter insulae with 96.5, 96.2 and 95.1 % sequence similarities, respectively. The sole respiratory quinone of strain PX7T was ubiquinone-10, and the dominant fatty acid was C18 : 1ω7c (80.2 %). The major polar lipids were phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, one unidentified aminolipid, one unidentified phospholipid and one unidentified lipid. The DNA G+C content of strain PX7T was 60.2 mol%. Based on the combination of phylogenetic analyses, phenotypic and chemotaxonomic data, strain PX7T is considered to represent a novel species within the genus Primorskyibacter in the family Rhodobacteraceae, for which the name Primorskyibacter marinus sp. nov. is proposed. The type strain of the new species is PX7T (=KCTC 42952T=MCCC 1H00196T).