The Sri Lankan Kandyan dwarf toad (Adenomus kandianus) was thought to be extinct. It’s still listed as extinct, and hadn’t been seen in almost 135 years. A. kandianus was first discovered in a freshwater stream in Sri Lanka in 1872. It was last seen in 1876. Exhaustive surveys had failed to find any trace of it until 2009, where a cataloging effort of the region’s forests spotted four unusual toads in a fast-flowing stream.
The scientists had been canvassing the 22,380-hectare Peak Wilderness Sanctuary. The warty, yellow-bellied toad had been gone for more than a century but reappeared. The scientists recorded its characteristics, such as size, shape, feet webbing, and skin texture. They also collected one of the animals for further study. It matched the descriptions of A. kandianus at the British Museum, and genetics had failed to match it to any known toad.
100 more A. kandianus were discovered in a recent trip to the area in a vicinity of 200 square meters. The scientists reported their findings in the journal Zootaxa. The small habitat range and the similar appearance to more common amphibian, the torrent toad (Adenomus dasi), are probably the reasons why the species eluded scientists for so long. It’s no longer considered to be extinct, but the Kandyan dwarf toad will still be endangered due to the small number found and the increasing human encroachment into the Sri Lankan forests.
Reference: “Back from the dead: The world’s rarest toad Adenomus kandianus rediscovered in Sri Lanka” by L. J. Mendis Wickramasinghe, Dulan Ranga Vidanapathirana and Nethu Wickramasinghe, 15 June 2012, Zootaxa.