Xanthophryne koynayensis (common names: Humbali Village toad, chrome-yellow toad, Koyna toad) is a species of toad in the family Bufonidae. It is endemic to the Western Ghats of India where it is known from Koyna (including Koyna Wildlife Sanctuary) in the Maharashtra state.[1] Formerly included in the genus Bufo it has been since made the type species for the genus Xanthophryne and is a sister species of Xanthophryne tigerina.[2]
Xanthophryne koynayensis has been described twice using the same materials[2] collected in connection with the Koyna Hydroelectric Project: first as Bufo koynayensis by Soman in 1963, and then as Bufo sulphureus by Grandison and Daniel in 1964.[2]
Xanthophryne koynayensis are relatively small toads: adult males measure 24mm32mm in snout–vent length.[2] The body is covered by small warts with black tips and dark brown in colour; there are yellow patches on the flanks, thighs, and shoulders. The tympanum is indistinct.
Xanthophryne koynayensis is a rare species. Its natural habitats are moist to wet evergreen forest and dry riparian grassland. It is threatened by habitat loss caused by agriculture and clear cutting of forests.