A collection of 12 strains, isolated from diseased tortoises and tentatively identified as [Pasteurella] testudinis-like based on phenotypic characters, was compared with three reference strains of [P.] testudinis. All strains could be separated from the reference strains with respect to 16S rRNA gene sequences, partial sequences of the rpoB housekeeping gene and by phenotypic characters. Based upon differences in 16S rRNA and rpoB gene sequences, the new isolates are suggested to represent a novel species in a new genus of the family Pasteurellaceae Pohl 1981, for which the name Chelonobacter oris gen. nov., sp. nov. is proposed. The type strain is 1662(T) (=CCUG 55632(T)=DSM 21392(T)). beta-Haemolysis and acid production from (+)-l-arabinose, dulcitol, (-)-d-mannitol, (+)-d-mannose, trehalose and salicin separated the new strains from members of existing genera of the family Pasteurellaceae, in addition to the beta-galactosidase, urease and alpha-glucosidase reactions. Differences in indole production, phosphatase, beta-glucosidase and production of acid from dulcitol and trehalose separated C. oris from [P.] testudinis. Several phenotypic characters separated C. oris from Bisgaard"s taxa 14 and 32.