A total of 13 Pasteurellaceae isolates from healthy freshwater turtles were characterized by genotypic and phenotypic tests. Phylogenetic analysis of partial 16S rRNA and rpoB gene sequences showed that the isolates investigated formed a monophyletic group. The closest related species based on 16S rRNA gene sequencing was Chelonobacter oris CCUG 55632(T) with 94.4 % similarity and the closest related species based on rpoB gene sequence comparison was [Pasteurella] testudinis CCUG 19802(T) with 91.5 % similarity. All the investigated isolates exhibited phenotypic characteristics of the family Pasteurellaceae. However, they could be separated from existing genera of the Pasteurellaceae by the following test results: indole, ornithine decarboxylase and Voges-Proskauer positive; and methyl red, urease and PNPG (alpha-glucosidase) negative. No X- or V-factor requirement was observed. A zone of beta-haemolysis surrounded the colonies after 24 h of incubation on bovine blood agar at 37 degrees C. Acid was produced from L-arabinose, dulcitol, D-mannitol, sucrose and trehalose. Representative strain ELNT2x(T) had a fatty acid profile that was characteristic for members of the Pasteurellaceae. ELNT2x(T) expressed only one respiratory quinone, ubiquinone-8 (100 %). The DNA G + C content of strain ELNT2x(T) was 42.8 mol%. On the basis of both phylogenetic and phenotypic evidence, it is proposed that the strains should be classified as representatives of a novel species of a new genus, Testudinibacter aquarius gen. nov., sp. nov. The type strain of Testudinibacter aquarius is ELNT2x(T) (=CCUG 65146(T)=DSM 28140(T)), which was isolated from the oral cavity of a captive eastern long-necked turtle (Chelodina longicollis) in Denmark in 2012.