A novel, Gram-negative, non-spore-forming, pleomorphic yellow-orange bacterial strain was isolated from a stadium seat. Strain CoronadoT falls within the Erythrobacteraceae family and the genus Porphyrobacter based on 16S rRNA phylogenetic analysis. This strain has Q-10 as the predominant respiratory lipoquinone, as do other members of the family. The fatty acid profile of this strain is similar to other Porphyrobacter, however CoronadoT contains predominately C18:1ω7cis and C16:0, a high percentage of the latter not being observed in any other Erythrobacteraceae. This strain is catalase-positive and oxidase-negative, can grow from 4-28 °C, at NaCl concentrations 0.1-1.5%, and at pH 6.0-8.0. On the basis of phenotypic and phylogenetic data presented in this study, strain CoronadoT represents a novel species in the Porphyrobacter genus for which the name Porphyrobacter mercurialis sp. nov. is proposed; the type strain is CoronadoT (=DSMZ 29971, =LMG 28700).