A Gram-negative, short rod-shaped bacterium, strain GA2-M15(T), was isolated from a sea-sand sample at Homi Cape, Pohang city, Republic of Korea. 16S rRNA gene sequence analysis demonstrated that this isolate was unique, showing 95.9 % sequence similarity to the type strain of Thalassobacter stenotrophicus and similarities of 94.0-95.2 % to the type strains of species of the genera Octadecabacter (94.4-95.2 %), Jannaschia (94.0-94.4 %) and Thalassobius (94.0-94.7 %). Chemotaxonomic characteristics (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine as the major polar lipids and C(18 : 1)omega7c as the predominant fatty acid) and DNA G+C content (56 mol%) were also similar to those of Thalassobacter stenotrophicus. 16S rRNA gene sequence similarity, physiological properties and some fatty acid components showed that strain GA2-M15(T) could be differentiated from Thalassobacter stenotrophicus. On the basis of these results, strain GA2-M15(T) is considered to represent a novel species of the genus Thalassobacter, for which the name Thalassobacter arenae sp. nov. is proposed. The type strain is GA2-M15(T) (=KACC 12675(T) =DSM 19593(T)).