[2][5] Atelopus longirostris was described by Edward Drinker Cope in 1868 based on a specimen collected by James Orton and which now appears to be lost.

[4][6] Previously, the species has been classified as extinct, due to huge declines probably related to the disease chytridiomycosis, climate change and habitat loss.

It was rediscovered in March 2016 when four adults (two males and two females) were located in Imbabura in two small forest patches in an area heavily modified for agriculture and livestock.

These individuals tested negative for chytridiomycosis and were brought to the Jambatu Research and Conservation Center in the hope of establishing a captive breeding population.

[5] Atelopus longirostris is historically known from the western slopes of the northern Ecuadorian Andes in the provinces of Esmeraldas, Imbabura, Pichincha, and Cotopaxi, at elevations between 200–2,500 m (660–8,200 ft) above sea level.