A Gram-stain-positive, non-spore-forming, yellow pigmented, non-motile, aerobic, short rod-shaped bacterial strain, designated CAU 1455(T), was isolated from marine sediment sand. Strain CAU 1455(T) grew optimally at 30 A degrees 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 1455(T) was affiliated to the genus Cellulosimicrobium and was most closely related to Cellulosimicrobium terreum DS-61(T) (similarity 97.9%). The strain possessed MK-9 (H-4) as the predominant menaquinone and anteiso-C-15:0 as 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 1455(T) and C. terreum DS-61(T) was 27.8%. Based on phenotypic, chemotaxonomic, and genetic data, strain CAU 1455(T) represents a novel species of the genus Cellulosimicrobium, for which the name Cellulosimicrobium arenosum sp. nov. is proposed. The type strain is CAU 1455(T) (= KCTC 49039(T) = NBRC 113062(T)).