A novel strain, designated MRN461(T), was isolated from a marine sponge in Micronesia. The 16S rRNA gene sequence of the isolate showed 95.6 % similarity with that of 'Microscilla furvescens' IFO (now NBRC) 15994. Phylogenetic analysis revealed that the isolate and 'Microscilla furvescens' IFO 15994 formed a distinct phyletic line within the family 'Flexibacteraceae'. Cells of strain MRN461(T) were Gram-negative, long filamentous rods, motile by gliding. Growth was observed at 15-40 degrees C (optimum, 33 degrees C), at pH 5.0-9.5 (optimum, pH 7.5) and in the presence of 0.5-7.0 % sea salts (optimum, 2.5 %). The major isoprenoid quinone was MK-7. The dominant fatty acids were summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c; 34.8 %), C(16 : 1)omega5c (21.6 %) and iso-C(16 : 1) (19.8 %). The DNA G+C content was 41.5 mol%. On the basis of evidence from our polyphasic taxonomic study, strain MRN461(T) is classified within a novel genus and species in the family 'Flexibacteraceae', for which the name Marinoscillum pacificum gen. nov., sp. nov. is proposed. The type strain of Marinoscillum pacificum is strain MRN461(T) (=KCCM 42325(T) =JCM 14064(T)). The misclassified species '[Microscilla] furvescens' is transferred to the new genus as Marinoscillum furvescens (ex Lewin 1969) nom. rev., comb. nov., with LMG 13023(T) (=DSM 4134(T) =ATCC 23129(T) =NBRC 15994(T)) as the type strain.