A tyrosine-metabolizing, Gram-stain-negative, strictly aerobic, non-spore-forming, curved-rod-shaped, motile (due to monopolar flagellum) marine bacterium, designated strain CC-PW-9T, was isolated from estuarine water off Pingtung, Taiwan. Strain CC-PW-9T not only shared highest 16S rRNA gene sequence similarities with Idiomarina representatives (96.4-93.4 %, n=26), but also formed a distinct phyletic lineage and coherent phylogenetic cluster associated with those species. Cells of strain CC-PW-9T grew with 6-12 % (w/v) NaCl, at 20-40 �XC and at pH 6-9. It produced predominant amounts of phosphatidylethanolamine, plus diphosphatidylglycerol, phosphatidylglycerol, phosphatidylserine, two unidentified phospholipids, an unidentified phosphoglycolipid, two unidentified lipids and an unidentified aminolipid in moderate to trace amounts. Fatty acids such as iso-C15 : 0, iso-C17 : 0 and iso-C17 : 1�s9c and/or C16 : 010-methyl (summed feature 9) were found in major amounts. The DNA G+C content was 51.1 mol%. Ubiquinone-8 (Q-8) was the sole respiratory quinone. Based on evidence from this polyphasic taxonomic study, strain CC-PW-9T is considered to represent a novel species of the genus Idiomarina, affiliated to the family Idiomarinaceae, for which the name Idiomarina tyrosinivorans sp. nov. is proposed. The type strain is CC-PW-9T (=JCM 19757T=BCRC 80745T).