A Gram-stain-positive, non-spore-forming, yellow pigmented, non-motile, aerobic, short rod-shaped bacterial strain, designated CAU 1455T, was isolated from marine sediment sand. Strain CAU 1455Tgrew optimally at 30 °C and at pH 7.5 in the presence of 1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CAU 1455Twas affiliated to the genus Cellulosimicrobium and was most closely related to Cellulosimicrobium terreum DS-61T(similarity 97.9%). The strain possessed MK-9 (H4) as the predominant menaquinone and anteiso-C15:0as the major cellular fatty acids. Peptidoglycan type was A4a (L-Lys-D-Glu2). The DNA G+C content was 74.3 mol% and the level of DNA-DNA relatedness between CAU 1455Tand C. terreum DS-61Twas 27.8%. Based on phenotypic, chemotaxonomic, and genetic data, strain CAU 1455Trepresents a novel species of the genus Cellulosimicrobium, for which the name Cellulosimicrobium arenosum sp. nov. is proposed. The type strain is CAU 1455T(= KCTC 49039T = NBRC 113062T).