A Gram-staining-negative, chemoheterotrophic, yellow-pigmented, gliding, catalase- and oxidase-positive, flexirubin-negative, strictly aerobic bacterium, designated strain IMCC9485(T), was isolated from a seawater sample collected from the Arctic Ocean. Optimal growth of strain IMCC9485(T) was observed at 25 °C, pH 7-8 and in the presence of 1.5-2.5 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IMCC9485(T) belonged to the genus Formosa and was closely related to Formosa algae KCTC 12364(T) (98.2 %) and Formosa agariphila KCTC 12365(T) (98.0 %). DNA-DNA relatedness between the new isolate and F. algae and F. agariphila was far lower than 70 %, which indicated that strain IMCC9485(T) is a novel genomic species of the genus Formosa. The major fatty acids (>10 %) were iso-C15 : 1G (13.7 %), C16 : 1ω7c and/or C16 : 1ω6c (13.4 %) and iso-C15 : 0 (12.3 %). The G+C content of the genomic DNA was 37.6 mol%. Strain IMCC9485(T) contained menaquinone-6 (MK-6) as the respiratory quinone and phosphatidylethanolamine, unknown aminophospholipids and unknown polar lipids as polar lipid constituents. On the basis of phylogenetic analyses and differential phenotypic characteristics, it is suggested that strain IMCC9485(T) ( = KACC 17484(T) = KCCM 42937(T) = NBRC 106080(T)) be assigned to the genus Formosa as the type strain of a novel species, for which the name Formosa arctica sp. nov. is proposed.