Bacterial strains Eant 3-9(T) and Eant 3-3, isolated from the gut of the termite Odontotermes formosanus, were characterized using a polyphasic taxonomic approach. Cells of these organisms were Gram-negative, non-pigmented, rod-shaped, non-endospore-forming and facultatively anaerobic. Phenotypic, physiological and genetic characteristics of the two strains were highly similar. Phylogenetic analyses using 16S rRNA gene sequences showed that strain Eant 3-9(T) formed a monophyletic branch towards the periphery of the evolutionary radiation occupied by the genus Trabulsiella; its closest neighbour was Trabulsiella guamensis DSM 16940(T) (98.1 % similarity). Genomic DNA-DNA relatedness between strains Eant 3-9(T) and Eant 3-3 was 96+/-4 %, indicating that they belong to a single species. Eant 3-9(T) displayed DNA-DNA relatedness values of 48+/-5 and 14+/-3 % with T. guamensis DSM 16940(T) and Salmonella typhimurium ATCC 13311(T), respectively, indicating that Eant 3-9(T) warrants novel species status in the genus Trabulsiella. Eant 3-9(T) and Eant 3-3 could be further distinguished from T. guamensis DSM 16940(T) using whole-cell protein profiles and a range of physiological and biochemical characteristics. It is evident from genotypic and phenotypic data that Eant 3-9(T) represents a novel species in the genus Trabulsiella, for which the name Trabulsiella odontotermitis sp. nov. is proposed. The type strain is Eant 3-9(T) (=BCRC 17577(T)=LMG 23580(T)); Eant 3-3 is a reference strain.