A Gram-stain-negative, aerobic, non-motile, non-spore-forming bacterial strain, designated JDTF-31T, was isolated from a tidal flat in Jindo, a South Korean island. Strain JDTF-31T grew optimally at 25 °C and in the presence of 2.0 % (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain JDTF-31T fell within the cluster comprising the type strains of Tenacibaculum species, joining the type strain of Tenacibaculum soleae. The novel strain exhibited 16S rRNA gene sequence similarity values of 98.3, 97.8 and 97.1 % to the type strains of T. soleae, Tenacibaculum haliotisand Tenacibaculum ovolyticum, respectively, and of 94.2-96.8 % to the type strains of the other Tenacibaculum species. Strain JDTF-31T contained MK-6 as the predominant menaquinone and iso-C15 : 0 and iso-C15 : 0 3-OH as the major fatty acids. The major polar lipids of strain JDTF-31T were phosphatidylethanolamine, one unidentified lipid and one unidentified aminophospholipid. The DNA G+C content of strain JDTF-31T was 31.3 mol% and its DNA-DNA relatedness values with the type strains of T. soleae, T. haliotis and T. ovolyticum were 16-27 %. The differential phenotypic properties, together with its phylogenetic and genetic data, revealed that strain JDTF-31T is separated from other recognized species of the genus Tenacibaculum. On the basis of the data presented, strain JDTF-31T represents a novel species of the genus Tenacibaculum, for which the name Tenacibaculuminsulae sp. nov. is proposed. The type strain is JDTF-31T (=KCTC 52749T=NBRC 112783T).