Strain ANT-18T, isolated from a water sample taken from the Longtoushan Spring in Taiwan, was characterized using a polyphasic taxonomic approach. Cells of strain ANT-18T were Gram-stain-negative, aerobic, motile by gliding rods that were surrounded by a thick capsule and it formed pink colonies. Growth occurred at 20-37 �XC (optimum, 25 �XC), at pH 6-8 (optimum, pH 7) and with 0-1 % NaCl (w/; optimum, 0 %). Phylogenetic analyses, based on 16S rRNA gene sequences, showed that strain ANT-18T belongs to the genus Hymenobacter and showed the highest levels of sequence similarity to Hymenobacter ocellatus Myx 2105T (97.8 %) and Hymenobacter paludis KBP-30T (97.7 %). Strain ANT-18T contained iso-C15 : 0, anteiso-C15 : 0, C18 : 0 and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) as the predominant fatty acids. The major isoprenoid quinone was MK-7. The polar lipid profile consisted of phosphatidylethanolamine, one uncharacterized aminolipid, two uncharacterized aminophospholipids, two uncharacterized glycolipids and seven uncharacterized lipids. The major polyamine was homospermidine. The genomic DNA G+C content of strain ANT-18T was 63.6 mol%. The DNA-DNA relatedness values of strain ANT-18T with respect to H. ocellatus Myx 2105T and H. paludis KBP-30T were less than 35 %. On the basis of the phylogenetic inference and phenotypic data, strain ANT-18T is recognized to be a representative of a novel species within the genus Hymenobacter. The name Hymenobacter gummosus sp. nov. is proposed, with strain ANT-18T (=BCRC 80966T=LMG 29477T=KCTC 52166T) as the type strain.