A bacterial strain, designated BAR1T, was isolated from a microbial mat growing on the surface of a barite chimney at the Loki's Castle Vent Field, at a depth of 2216 m. Cells of strain BAR1T were rod-shaped, Gram-reaction-negative and grew on marine broth 2216 at 10-37 °C (optimum 27-35 °C), pH 5.5-8.0 (optimum pH 6.5-7.5) and 0.5-5.0 % NaCl (optimum 2 %). The DNA G+C content was 57.38 mol%. The membrane-associated major ubiquinone was Q-10, the fatty acid profile was dominated by C18 : 1ω7c (91 %), and the polar lipids detected were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid, one unidentified lipid and one unidentified phospholipid. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BAR1T clustered together with Rhodobacterales bacterium PRT1, as well as the genera Halocynthiibacter and Pseudohalocynthiibacter in a polyphyletic clade within the Roseobacter clade. Several characteristics differentiate strain BAR1T from the aforementioned genera, including its motility, its piezophilic behaviour and its ability to grow at 35 °C and under anaerobic conditions. Accordingly, strain BAR1T is considered to represent a novel genus and species within the Roseobacter clade, for which the name Profundibacter amoris gen. nov., sp. nov. is proposed. The type strain is Profundibacter amoris BAR1T (=JCM 31874T=DSM 104147T).