A study was undertaken to determine the prevalence and diversity of species of the genus Arcobacter in pig and dairy cattle manure, which led to the identification of strains AF1440^T, AF1430 and AF1581. Initially identified as Arcobacter butzleri based on colony morphology and initial PCR-confirmation tests, analyses of 16S rRNA gene sequences of these strains confirmed that they belonged to the genus Arcobacter and were different from all known species of the genus. The isolates formed a distinct group within the genus Arcobacter based on their 16S rRNA, gyrB, rpoB, cpn60, gyrA and atpA gene sequences and fatty acid profiles. Their unique species status was further supported by physiological properties and DNA–DNA hybridization that allowed phenotypic and genotypic differentiation of the strains from other species of the genus Arcobacter. The isolates were found to be oxidase, catalase and esterase positive and urease negative; they grew well at 30 °C under microaerophilic conditions and produced nitrite and acetoin. Based on their common origin and various physiological properties, it is proposed that the isolates are classified as members of a novel species with the name Arcobacter lanthieri sp. nov. The type strain is AF1440^T ( = LMG 28516^T = CCUG 66485^T); strains AF1430 ( = LMG 28515 = CCUG 66486) and AF1581 ( = LMG 28517 = CCUG 66487) are reference strains.