A novel facultatively anaerobic and Gram-stain-negative bacterial strain, designated 5E3T, was isolated from intertidal sediments of Xiaoshi Island of Weihai, People's Republic of China. Cells of strain 5E3T were long rod-shaped with widths of 0.3-0.5μm and lengths of 4.0-6.0μm. Optimum growth of strain 5E3T occurred at 33°C, pH 6.5-7.0 and with 3% (w/v) NaCl. Oxidase activity was negative but catalase activity was weakly positive. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain 5E3T was most closely related to 'Maribellus comscasis' WC007 (99.5%), followed by M. sediminis MCCC 1K04285T (95.9%) and M. luteus XSD2T (95.6%). Genome comparisons between strain 5E3T and strain 'M. comscasis' WC007, using average nucleotide identity (ANI) value (93.0%) and DNA-DNA hybridization (DDH) value (50.1%), confirmed low genome relatedness. The major cellular fatty acids (≥ 10%) were iso-C15:0 and iso-C17:0 3-OH. The sole respiratory quinone was MK-7. The polar lipids consisted of phosphatidylethanolamine (PE), one unidentified aminolipid (AL) and three unidentified lipids (L1, L2, L3). The DNA G + C content was 37.9mol%. According to the integrated results of phylogenetic, physiological, biochemical and chemotaxonomic characteristics, we propose that strain 5E3T represents a novel species of the genus Maribellus, for which the name Maribellus maritimus sp. nov. is proposed. The type strain is 5E3T (= KCTC 82744T = MCCC 1H00473T).