A novel Gram-negative, rod shaped, motile, non-spore-forming, aerobic, brominated flame retardant hexabromocyclododecane-assimilating bacterium, designated strain GYP-17T, was isolated from a pool of marine Spirulina platensis cultivation, Sanya, China. Colonies on 1/10 strength of marine Glycerol Enriched Medium plates were circular, dark-brown, 1–2 mm in diameter, and with regular margins. Growth occurred at 10–45 °C, 1–10 % (w/v) NaCl and pH of 7–9. The polar lipids were composed of phosphatidylethanolamine, three unidentified phospholipids and one unidentified polar lipid. The major fatty acids were iso-C17:1ω9c/10-methyl-C16:0 (summed feature 9, 20.75 %), iso-C15:0 (17.70 %) and C16:0 (6.40 %). The major respiratory quinone was Q-8. The DNA G + C content of the type strain was 53.6 mol%. Phylogenetic analysis revealed that strain GYP-17T was a member of the genus Aliidiomarina and closely related to Aliidiomarina haloalkalitolerans with a 16S rDNA sequence similarity of 96.36 %. Results from the polyphasic taxonomy study support the conclusion that strain GYP-17T represents a novel Aliidiomarina species, for which the name Aliidiomarina sanyensis sp. nov. is proposed. The type strain of A. sanyensis is GYP-17T (=KCTC 32218T =LMG 27471T).