Abstract: We describe a new species, Fejervarya muangkanensis sp. nov ., based on a series of specimens collected from Ban Tha Khanun, Thong Pha Phum District, Kanchanaburi Province, Thailand. The new species is easily distinguished from its congeners by morphological and molecular data, and can be diagnosed by the following characters: (1) small size (adult male snout-vent length (SVL) 33.5 mm; female SVL 40.0-40.9 mm); (2) tympanum small, discernible but unclear; (3) poorly developed toe webbing; (4) no lateral line system in adults; (5) characteristic "Fejervaryan" lines present in females; and (6) femoral glands absent. Molecular phylogenetic analysis of mitochondrial 16S rRNA further supports it as a distinct lineage and distinguishes it from its congeners for which sequences are available.