A marine bacterium, strain Pol012(T), was isolated from the Mediterranean sponge Axinella polypoides and subsequently characterized as belonging to subphylum 1 of the phylum 'Verrucomicrobia'. Strain Pol012(T) was non-motile, Gram-negative, coccoid or rod-shaped and red in colour. The menaquinones MK-8 and MK-9 were detected. The G+C content of the genomic DNA was 50.9 mol%. Growth was possible at temperatures between 8 and 30 degrees C and at pH values between 6.8 and 8.2. The closest cultured relative of strain Pol012(T) was Akkermansia muciniphila (83 % sequence similarity), while the closest environmental 16S rRNA gene sequence was the marine clone Arctic96BD-2 (95 % sequence similarity). Strain Pol012(T) is the first marine pure-culture representative of 'Verrucomicrobia' subphylum 1 and represents a novel genus and species, for which the name Rubritalea marina gen. nov., sp. nov. is proposed. The type strain is Pol012(T) (=DSM 177716(T)=CIP 108984(T)).