In this study, we reported two gram-negative bacteria that were isolated from bitterns, designated as SKKU-TP7(T) and SKKU-TP20, representing a novel species of Citrobacter. Based on the 16S rRNA gene sequences, the two strains were found to be closely related and showed the highest pairwise similarity with Citrobacter farmeri CDC 2992-81(T) (97.1-97.3 %) and other Citrobacter species. Cellular fatty acid analysis revealed that the profiles of strains SKKU-TP7(T) and SKKU-TP20 were similar to those of related species of Citrobacter. The major cellular fatty acids were C16:0 (31.5 %), summed feature 3 (C16:1 omega 7c, C16:1 omega 6c, 19.7 %), summed feature 8 (C18:1 omega 7c, C18:1 omega 6c, 11.9 %), C17:0 cyclo (10.7 %), and summed feature 2 (C12:0 aldehyde/unknown 10928, 9.5 %). Although the strains could utilize sucrose and raffinose as a carbon source, they did not produce ornithine decarboxylase and urease. The biochemical and genotypic characteristics indicate that strains SKKU-TP7(T) and SKKU-TP20 represent a novel species of Citrobacter, for which the name Citrobacter bitterns sp. nov. is proposed. The type strain is SKKU-TP7(T) (=KCTC 42139(T) = JCM 30009(T)).