Three bacterial strains, designated CCUG 51397 T , CCUG 53736 and CCUG 53920, isolated from water samples taken at different locations in southern Sweden were studied to determine their taxonomic position using a polyphasic approach. Comparative analysis of 16S rRNA gene sequences showed that these bacteria had ,93 % sequence similarity to all described species of the genera Sediminibacterium, Lacibacter, Flavihumibacter, Flavisolibacter, Niabella, Niastella, Segetibacter, Parasegetibacter, Terrimonas, Ferruginibacter, Filimonas and Chitinophaga. The three organisms grouped most closely with Sediminibacterium salmoneum NJ-44 T but showed only 92.5 % sequence similarity to this strain, the only recognized species of this genus. The fatty acid profiles showed large amounts of iso-C 15 : 0 , iso-C 17 : 0 3-OH and iso-C 15 : 1 G with smaller amounts of iso-C 15 : 0 3-OH, iso-C 16 : 0 3-OH and other fatty acids, which differentiated the novel strains from related genera. Biochemical tests performed on strains CCUG 51397 T , CCUG 53736 and CCUG 53920 also gave different results from those of Sediminibacterium salmoneum NJ-44 T and other related genera. Based on this evidence, strains CCUG 51397 T , CCUG 53736 and CCUG 53920 represent a novel species of a new genus, for which the name Hydrotalea flava gen. nov., sp. nov. is proposed. The type strain of Hydrotalea flava is CCUG 51397 T (5CCM 7760 T ). A formal allocation of the genera Sediminibacterium, Lacibacter, Flavihumibacter, Flavisolibacter, Niabella, Niastella, Segetibacter, Parasegetibacter, Terrimonas, Ferruginibacter, Filimonas and Chitinophaga to the family Chitinophagaceae fam. nov. is also proposed.Three bacterial strains, designated CCUG 51397 T , CCUG 53736 and CCUG 53920, were isolated from different water samples taken in July 2005 and November and December 2006 in southern Sweden and were studied using a polyphasic approach. Cells of the isolates were Gram-reaction-negative and formed orange-pigmented colonies. From the results of initial 16S rRNA gene sequence analysis, it was evident that these strains, which had identical 16S rRNA gene sequences, could be allocated to the phylum Bacteroidetes. The most closely related species was found to be Sediminibacterium salmoneum (Qu & Yuan, 2008) et al., 2010). All of these genera formed a distinct cluster in the 16S rRNA gene sequence-based tree and showed some phenotypic similarities. Here, we propose that these three novel strains represent a novel genus, Hydrotalea gen. nov., and in addition formally propose that the genera Chitinophaga, Sediminibacterium,