A novel Gram-stain-positive actinobacterium, designated HIs16-32T, was isolated from a sand sample collected from a mangrove tidal flat in Japan and its taxonomic position was investigated by a polyphasic approach. The cells of strain HIs16-32T were Gram-stain-positive, rod-shaped, non-motile and non-endospore-forming. Strain HIs16-32T contained glutamic acid, glycine and lysine in the peptidoglycan; however, alanine was absent. Galactose and mannose were detected as cell-wall sugars. The isoprenoid quinones were identified as MK-11, MK-12 and MK-10, and the major fatty acids as anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content was determined to be 72.2 mol%. Phylogenetic analyses based on 16S rRNA gene sequence comparison revealed that strain HIs16-32T was related to members of the family Microbacteriaceae but did not form a reliable cluster with any known members of the family. The highest 16S rRNA gene sequence similarity values were obtained with species of the genera Herbiconiux(96.1-96.8 %), Plantibacter(96.5-96.7 %) and Schumannella (96.7 %). However, strain HIs16-32T was distinguishable from the phylogenetically related genera in terms of chemotaxonomic characteristics and phylogenetic relationship. Therefore, strain HIs16-32T is concluded to represent a novel genus and species of the family Microbacteriaceae, for which the name Arenivirga flava gen. nov., sp. nov. is proposed. The type strain of A. flava is HIs16-32T (=NBRC 112289T=TBRC 7038T).