A novel marine, heterotrophic, aerobic, pigmented, non-motile bacterium was isolated from a bottom sediment sample collected from Troitsa Bay in the Gulf of Peter the Great, Sea of Japan, during June 2000. 16S rDNA sequence analysis revealed that this bacterium was a member of the family FLAVOBACTERIACEAE: On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic analyses, the bacterium was shown to belong to a novel species of the genus Arenibacter, for which the name Arenibacter troitsensis sp. nov. is proposed. The type strain is KMM 3674(T) (=JCM 11736(T)).