An orange-coloured, rod-shaped, Gram-reaction-negative and aerobic bacterial strain, designated KYW589(T), was isolated from seawater collected from Gwangyang Bay, Republic of Korea. The isolate required sea salts for growth. Gliding motility was observed. Flexirubin-type pigments were absent. Major cellular fatty acids (>10% of the total) were iso-C15:0, iso-C17:0 3-OH, iso-C15:1 G, C16:0, iso-C15:0 3-OH and C18:0. The main polar lipids were phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids. The predominant isoprenoid quinone was MK-6. The DNA G+C content was 38.6 ± 0.7 mol% (mean ± sd of three determinations). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KYW589(T) belongs to the family Flavobacteriaceae, and was related to the genus Algibacter. Based on data from a study using a polyphasic taxonomic approach, it is proposed that strain KYW589(T) represents a novel species belonging to the genus Algibacter, for which the name Algibacter aquimarinus sp. nov. is proposed. The type strain is KYW589(T) (=KCTC 23928(T) =JCM 18287(T)). Reclassification of Pontirhabdus pectinivorans Yi et al. 2011 to the genus Algibacter, as Algibacter pectinivorans comb. nov. (type strain JC2675(T) =KACC 14153(T) =JCM 17107(T)), is also proposed.