By Richard Black
Environment Correspondent, BBC News website
Scientists have sighted a spectacular South American frog which had been feared extinct for a decade.
The painted frog is found only in a small remote region of Colombia, and the last sighting dates back to 1995.
Conservationists believed it had gone extinct, principally due to a fungal disease, chytridiomycosis, which has caused enormous harm to many species.
The team behind the rediscovery say it gives hope that other amphibians may be able to survive fungal attack.
Chytridiomycosis is the main reason behind the worldwide decline in amphibians, which sees about one third of all species threatened with extinction.
The painted frog Atelopus ebenoides marinkellei is believed to exist only in the Boyaca region of Colombia.
It belongs to a family which includes a number of species known as harlequin frogs.
The internationally-recognised Red List of Threatened Species says of the painted frog that it "...has not been recorded since 1995, despite attempts to locate it.
"It appears to have declined seriously, and has possibly disappeared."
Now, however, it has re-appeared, spotted in early May by Professor Carlos Rocha and a team of researchers from the Pedagogical and Technological University of Colombia (UPTC) in Boyaca.
"The scientific importance of the finding must motivate us to adopt urgent measures toward saving the last of these amphibians, both in the wild and through captive breeding programmes," said Fabio Arjona, executive director of Conservation International in Colombia, which supported Professor Rocha's expedition.
"That will require a lot of support from the local and international communities."
Amphibians are one of the most threatened groups of organisms in the world.
Their skins easily absorb pollutants, the habitats of many are being squeezed by human expansion, and some species are hunted.
But the single biggest threat is chytridiomycosis, a frequently fatal disease caused by the Batrachochytrium dendrobatidis fungus.
The Andes provides a graphic illustration of how devastating it can be.
In this "hotspot" of amphibian diversity which includes parts of Colombia, Ecuador, Peru and Venezuela, 42 of the 113 species of Atelopus have experienced population declines of up to 50%.
Last year a coalition of conservation groups adopted the Amphibian Conservation Action Plan, a global project aimed at stemming species loss.
So severe was the situation, they concluded, that some species could not be conserved in the wild; the only option would be to rear them in captivity, despite the huge expense which that would entail.
But the painted frog's rediscovery, according to Conservation International, gives reason to hope that some other species which had apparently succumbed to chytrodiomycosis may still be clinging to a precarious existence, and perhaps even developing resistance to the fungus.