An aerobic, Mn(II)-oxidizing, Gram-negative bacterium, strain 8047T, was isolated from a deep-sea hydrothermal vent plume in the south-west Indian Ocean. The strain was rod-shaped and motile with a terminal flagellum, and formed yellowish colonies. It produced catalase and oxidase, hydrolysed gelatin and reduced nitrate. 16S rRNA gene sequence analysis showed that strain 8047T belonged to the order Rhizobiales of the class Alphaproteobacteria , and was phylogenetically most closely related to the genus Fulvimarina , sharing 94.4 % sequence identity with the type strain of the type species. The taxonomic affiliation of strain 8047T was supported by phylogenetic analysis of four additional housekeeping genes, gyrB, recA, rpoC and rpoB. The predominant respiratory lipoquinone of strain 8047T was Q-10, the major fatty acid was C18 : 1ω7c and the DNA G+C content was 61.7 mol%. On the basis of the phenotypic and genotypic characteristics determined in this study, strain 8047T represents a novel species within the genus Fulvimarina , for which the name Fulvimarina manganoxydans sp. nov. is proposed. The type strain is strain 8047T ( = CGMCC1.10972T = JCM 18890T).