A pale yellow-colored, moderately halophilic, Gram-negative, catalase- and oxidase-positive, non-sporulating, rod-shaped, motile, aerobic bacterium, designated strain JSM 073008(T), was isolated from a sea anemone (Anthopleura xanthogrammica) collected from Naozhou Island, Leizhou Bay, South China Sea. The organism was able to grow with 1-20% (w/v) total salts (optimum, 5-10%), at pH 6.0-10.0 (optimum, pH 7.5) and 10-40 degrees C (optimum, 25-30 degrees C). The major cellular fatty acids were C(16:0), C(16:1) omega7c/iso-C(15:0) 2-OH and C(18:1) omega7c. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid. The predominant respiratory quinone was Q-8 and the genomic DNA G + C content was 47.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 073008(T) should be assigned to the genus Alteromonas, being most closely related to Alteromonas hispanica F-32(T) (sequence similarity 96.9%), followed by Alteromonas genovensis LMG 24078(T) (96.6%) and Alteromonas litorea TF-22(T) (96.4%). The sequence similarities between the novel isolate and the type strains of other recognized Alteromonas species ranged from 95.9% (with Alteromonas stellipolaris ANT 69a(T)) to 94.5% (with Alteromonas simiduii BCRC 17572(T)). The combination of phylogenetic analysis, phenotypic characteristics and chemotaxonomic data supported the view that strain JSM 073008(T) represents a new species of the genus Alteromonas, for which the name Alteromonas halophila sp. nov. is proposed. The type strain is JSM 073008(T) (=CCTCC AA 207035(T) = KCTC 22164(T)).