A bacterium designated strain Liujia-146(T) was isolated in the Tainan area of southern Taiwan from root nodules of the aquatic legume Neptunia oleracea. 16S rRNA gene sequence analysis indicated that strain Liujia-146(T) was highly similar to Labrys monachus VKM B-1479(T) (97.8 %) and Labrys methylaminiphilus JLW10(T) (95.5 %) and belonged to the order Rhizobiales in the Alphaproteobacteria. On the basis of phylogenetic analysis, DNA-DNA hybridization data, physiological and biochemical characteristics and fatty acid compositions, the organism was shown to belong to the genus Labrys whilst representing a novel species within this genus. We propose to classify strain Liujia-146(T) (=BCRC 17578(T)=LMG 23578(T)) as the type strain of Labrys neptuniae sp. nov.