Four yellow-pigmented, Gram-negative, motile strains were isolated from the glassy rind of submarine basaltic lava from the Jan Mayen area of the Norwegian/Greenland Sea at a depth of 1300 m below sea level. The four strains had identical 16S rRNA gene sequences and were indistinguishable in all phenotypic and chemotypic tests performed, indicating that they belonged to the same species. The strains had an obligately aerobic chemo-organotrophic metabolism. The strains were capable of growth at temperatures between -2 and 34 degrees C, at pH between 6.5 and 8.6, and at sea salt concentrations between 3 and 60 g l(-1). The strains were able to utilize organic acids, amino acids and sugars but not alcohols; they were also capable of hydrolysing a wide range of macromolecules. The predominant fatty acids were 15 : 0 iso, 15 : 1 iso, 15 : 0 iso 3-OH and 17 : 0 iso 3-OH. The mean DNA G+C content of the strains was 31.4 mol%. 16S rRNA gene sequence analysis indicated that the strains were affiliated to the genera Gaetbulibacter and Algibacter. However, phenotypic characteristics, especially aerobic metabolism, suggested that the strains should be placed within a new genus. On the basis of the polyphasic characterization of the four strains, it is suggested that the strains be included in the family Flavobacteriaceae as representatives of a novel species in a new genus, for which the name Flaviramulus basaltis gen. nov., sp. nov. is proposed. The type strain is H35(T) (=CIP 109091(T)=DSM 18180(T)).