Four bacterial strains, SN-14T, SN-4, M6-46 and M6-58B, were isolated from water of ponds of two salterns located in Huelva (Spain). They were Gram-stain-negative, aerobic and slightly curved rods. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the four strains belong to the genus Idiomarina, being related most closely to Idiomarina fontislapidosi F23T (98.4-98.0% sequence similarity), Idiomarina seosinensis CL-SP19T (98.3-98.0%), Idiomarina piscisalsi TPS4-2T (97.9-97.4%), Idiomarina baltica OS145T (97.5-97.4%) and Idiomarina zobellii KMM 231T (97.6-97.0%). The level of similarity with the type species of the genus, Idiomarina abyssalis KMM 227T, was 97.2-96.7%. The novel strains exhibited optimal growth at 5-10% (w/v) total salts, pH 7 and 37 °C. The major fatty acids of strain SN-14T were iso-C15 : 0, iso-C17 : 0, C18 : 1ω7c/C18 : 1ω6c, C16 : 0 and iso-C17 : 1ω9c/C16 : 0 10-methyl. The DNA G+C content range was 47.6-50.8 mol%. The level of DNA-DNA relatedness between strain SN-14T and I. fontislapidosi F23T was 13%, while those between strain SN-14T and the other three new isolates were between 77 and 99%. These data demonstrated that the four isolates constitute a novel species of the genus Idiomarina. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, the four strains represent a novel species of the genus Idiomarina, for which the name Idiomarina aquatica sp. nov. is proposed. The type strain is SN-14T ( = CCM 8471T = CECT 8360T = LMG 27613T).