A bacterial strain designated KMB9T was isolated from a freshwater pond in Taiwan and characterized using a polyphasic taxonomy approach. Cells of strain KMB9T were Gram-stain-negative, aerobic, poly-�]-hydroxybutyrate-accumulating, motile by means of a monopolar flagellum, non-spore-forming and rods surrounded by a thick capsule and forming white-coloured colonies. Growth occurred at 20-40 �XC (optimum, 25-37 �XC), at pH 6.5-7.5 (optimum, pH 7.0) and with 0-0.5 % NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene and four housekeeping gene sequences (recA, rpoA, rpoB and atpD) showed that strain KMB9T forms a distinct phyletic line within the family Alcaligenaceae, and the levels of 16S rRNA gene sequence similarity to its closest relatives with validly published names were less than 93.3 %. The predominant fatty acids were summed feature 3 (comprising C16 : 1�s7c and/or C16 : 1�s6c), C16 : 0 and C18 : 1�s7c. The major isoprenoid quinone was Q-8. The major polyamine was putrescine. The polar lipid profile revealed the presence of phosphatidylethanolamine, phosphatidylglycerol and several uncharacterized aminophospholipids, aminolipids, phospholipids and lipids. The genomic DNA G+C content of strain KMB9T was 54.5 mol%. On the basis of the genotypic and phenotypic data, strain KMB9T represents a novel species of a new genus in the family Alcaligenaceae, for which the name Parvibium lacunae gen. nov., sp. nov. is proposed. The type strain is KMB9T (=BCRC 81053T=LMG 30055T=KCTC 52814T).