A Gram-stain-negative, slightly curved, rod-shaped bacterial strain CAU 1517 was isolated from marine sediment in Busan, the Republic of Korea. The taxonomic position of strain CAU 1517 was investigated via a polyphasic approach comprising phenotypic, chemotaxonomic and phylogenetic properties. Strain CAU 1517 grew optimally at 30 °C, pH 7. 5 and in the presence of 7% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that strain CAU 1517 belongs to the genus Halarcobacter and is most closely related to Halarcobacter bivalviorum LMG 26154 (96.5% similarity). The average nucleotide identity and digital DNA-DNA hybridization values between strain CAU 1517 and members of genus Halarcobacter ranged from were 76.7-78.0% and 19.5-21.2%, respectively. The strain contained menaquinone-6 (MK-6) as the only respiratory quinone, and C, summed feature 3 (C ω7c/C ω6c), and summed feature 8 (Cω7c/Cω6c) as the major fatty acids. The polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylethanolamine, and two unidentified aminophospholipids. The G+C content was 28.2 mol%. Therefore, it has been demonstrated that the isolate represents a novel species of the genus Halarcobacter, for which the name Halarcobacter arenosus sp. nov., is proposed. The type strain is CAU 1517 (=KCTC 72232 =NBRC 113955).