A non-motile, rod-shaped bacterium, designated strain WPCB133(T), was isolated from freshwater collected from the Woopo wetland (Republic of Korea). Cells were Gram-reaction-negative, aerobic and catalase- and oxidase-positive. The major fatty acids were iso-C(15 : 0) and anteiso-C(15 : 0). The strain contained MK-7 as the major isoprenoid quinone. The DNA G+C content was 47 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain WPCB133(T) forms an independent lineage within the genus Mucilaginibacter. Strain WPCB133(T) was distantly related to Mucilaginibacter kameinonensis SCK(T) (94.7 % sequence similarity), Mucilaginibacter paludis TPT56(T) (94.5 %) and Mucilaginibacter gracilis TPT18(T) (94.4 %). Phenotypic characteristics distinguished strain WPCB133(T) from members of the genus Mucilaginibacter. On the basis of evidence presented in this study, strain WPCB133(T) represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter rigui sp. nov. is proposed. The type strain is WPCB133(T) (=KCTC 12534(T) =NBRC 101115(T)). An emended description of the genus Mucilaginibacter is also proposed.