Genus IX. Cellulophaga

The genus Cellulophaga is a member of the family Flavobacteriaceae, making up a relatively distinct if somewhat broad phylogenetic sublineage (see Taxonomic comments). The genus includes five species, Cellulophaga lytica, Cellulophaga algicola, Cellulophaga baltica, Cellulophaga fucicola, and Cellulophaga pacifica. Cellulophaga species form a single 16S rRNA gene cluster that is composed of two distinct subgroups. Cellulophaga lytica and Cellulophaga fucicola form one subgroup, while Cellulophaga algicola, Cellulophaga baltica, and Cellulophaga Pacifica form the second subgroup. These subgroups differ in terms of their 16S rRNA gene sequences by approximately 5-6%. It would seem that there could be grounds to split the genus into two separate sections; however, at present, this is very difficult to justify owing to the many distinct phenotypic and chemotaxonomic features that Cellulophaga species share.