A total of 17 bacterial isolates from northern elephant seals, tentatively classified within the family Pasteurellaceae, were further 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, closely related to the genus Bisgaardia within the family Pasteurellaceae. The rpoB gene sequence similarity was 97.2-100 % within the group and 16S rRNA gene sequence comparisons showed 99.2-99.8 % similarity within the group. According to 16S rRNA gene sequence analysis, the most closely related species with a validly published name was Bisgaardia hudsonensis with 96.9 % similarity and the most closely related species based on rpoB sequence comparison was Bisgaardia genomospecies 1 with an rpoB sequence similarity of 90.9 %. All the isolates investigated exhibited the phenotypic characteristics of the family Pasteurellaceae. However, these isolates could be separated from existing species of the genus Bisgaardia by the following characteristics: ability to grow at 42 °C, and acid production from lactose, melibiose, raffinose and l-rhamnose, but not from d-mannitol or trehalose. On the basis of both phylogenetic and phenotypic evidence, it is proposed that the strains should be classified as representatives of a novel species within the genus Bisgaardia: Bisgaardia miroungae sp. nov. The type strain, Wildatric(T) ( = CCUG 65148(T) = DSM 28141(T)), was isolated from the oral cavity of a wild northern elephant seal at The Marine Mammal Center, California, USA in 2011. To include the novel species, the description of the genus Bisgaardia has been emended.