Abstract A new Vibrio strain K08M4 T was isolated from the broad-nosed pipefish Syngnathus typhle in the Kiel Fjord. Infection experiments revealed that K08M4 T is highly virulent for juvenile pipefish. Cells of strain K08M4 T are Gram-stain-negative, curved rod-shaped and motile by means of a single polar flagellum. The strain can grow aerobically at 9 to 40°C, at pH 4 to 10.5 and tolerates up to 12% (w/v) NaCl. The most prevalent (> 10%) cellular fatty acids of K08M4 T were C 16:1 ω 7 c and C 16:0. Whole-genome comparisons revealed that K08M4 T represents a separate evolutionary lineage which is distinct from other Vibrio species and falls within the Vibrio Splendidus clade. The genome is 4,886,292 bp in size, consists of two circular chromosomes (3,298,328 bp, 1,587,964 bp), and comprises 4,178 protein-coding genes and 175 RNA genes. In this study, we describe the phenotypic features of the new isolate and present the annotation and analysis of its complete genome sequence. Based on these data, the new isolate represents a new species for which we propose the name Vibrio syngnathi . The type strain is K08M4 T (=DSM 109818 T ). Supplementary material One supplementary figure and six supplementary table are available with the online version of the Manuscript.