A novel aerobic, gram-negative bacterial strain, designated 17X/A02/237(T), was isolated from waters of the coastal north-western Mediterranean Sea. Cells were motile straight rods and formed dark-grey colonies on marine agar medium. Strain 17X/A02/237(T) contained ubiquinone Q-8 and its major fatty acids were C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH, C(18 : 1)ω7c, C(16 : 0), C(18 : 0) and C(10 : 0) 3-OH. The G+C content of the genomic DNA was 47.5 mol%. Phylogenetic analysis of the 16S rRNA gene sequence placed the strain in the class Gammaproteobacteria. Based on 16S rRNA gene sequence data, as well as physiological and biochemical characteristics, this isolate represents a novel species of a new genus, for which the name of Eionea nigra gen. nov., sp. nov. is proposed. The type strain is 17X/A02/237(T) ( = DSM 19752(T) = CIP 109759(T) = MOLA 288(T)).