A marine bacterial strain, designated A71(T), was isolated from marine algae collected from the South Sea, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain A71(T) belonged to the family Flavobacteriaceae and was closely related to Aequorivita antarctica SW49(T) (96.5 % sequence similarity). Cells of strain A71(T) were Gram-negative, aerobic, oxidase-negative, catalase-positive, yellow/orange-pigmented and non-motile. The major fatty acids were iso-C(15 : 0) (20.6 %), iso-C(17 : 1)omega9c (13.3 %), anteiso-C(15 : 0) (13.1 %), iso-C(17 : 0) 3-OH (12.7 %) and summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c; 6.6 %). The DNA G+C content was 36.9 mol%. Several phenotypic characteristics served to differentiate the isolate from recognized members of the genus Aequorivita. Data from this polyphasic study clearly demonstrated that strain A71(T) represents a novel species of the genus Aequorivita. The name Aequorivita capsosiphonis sp. nov. is proposed, with strain A71(T) (=KCTC 22183(T) =JCM 15070(T)) as the type strain. In addition, an emended description of the genus Aequorivita is presented.