Strain KYPY9T, isolated from the Funglin Stream in Taiwan, was characterized using a polyphasic taxonomy approach. Cells of KYPY9T were Gram-staining-negative, strictly aerobic, motile by means of a single polar flagellum, rod-shaped and formed light yellow colonies. Optimal growth occurred at 20-25 �XC, at pH 7 and with 0 % NaCl. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that KYPY9T represented a member of the genus Undibacterium and the sequence similarity between the 16S rRNA genes of KYPY9T and of the type strains of other species of the genus Undibacterium ranged from 94.1 to 98.0 %. The closest relatives of KYPY9T were Undibacterium seohonense SHS5-24T (98.0 %) and Undibacterium macrobrachii CMJ-9T (97.0 %). KYPY9T had summed feature 3 (C16 : 1�s7c and/or C16 : 1�s6c) and C16 : 0 as the predominant fatty acids. The major cellular hydroxy fatty acid was C10 : 0 3-OH. KYPY9T had phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol as the predominant polar lipids. The polyamine profile was composed of the major compound 2-hydroxyputrescine and moderate amounts of putrescine. The major respiratory quinone was Q-8 and the DNA G+C content was 47.4 mol%. The DNA-DNA relatedness of KYPY9T with respect to Undibacterium seohonense SHS5-24T and Undibacterium macrobrachii CMJ-9T was less than 35 %. On the basis of the phylogenetic inference and phenotypic data, KYPY9T was recognized as a representative of a novel species within the genus Undibacterium. The name Undibacterium amnicola sp. nov. is proposed, with KYPY9T (=BCRC 81009T=LMG 29730T=KCTC 52442T) as the type strain.