The gram-reaction-negative, motile, facultatively anaerobic, catalase-positive, oxidase-positive bacterial strain M3-4(T) was isolated from black sea sand and subjected to a taxonomic study. Cells of strain M3-4(T) have monotrichous flagella, grow optimally at 37A degrees C and at pH 7-8 in the presence of 1-4% (w/v) NaCl and hydrolyze casein, starch and l-tyrosine. According to phylogenetic analyses using 16S rRNA gene sequences, strain M3-4(T) belongs to the genus Photobacterium and is most closely related to Photobacterium rosenbergii LMG 22223(T) (97.4%) and P. gaetbulicola KCTC 22804(T) (96.6%). The DNA-DNA relatedness value between M3-4(T) and P. rosenbergii LMG 22223(T) was 21.5%. The DNA G+C mol% of strain M3-4(T) was 53.6. The major cellular fatty acid of strain M3-4(T) was a summed feature 3 consisting of C-16:1 omega 7c and/or iso-C-15:0 2-OH (35.0%), followed by C-16:0 (25.4%) and C-18:1 omega 7c (16.8%). These data suggest that strain M3-4(T) represents a novel species in genus Photobacterium, for which the name P. atrarenae sp. nov. is proposed. The type strain is M3-4(T) (= KCTC 23265(T) = NCAIM B 02414(T)).