This species occurs in humid montane forest in central Costa Rica in the Cordilleras Central and Talamanca in Costa Rica from 1,100-2,200m asl.
Habitat and Ecology
It occurs and reproduces in stream margins in premontane rainforest and lower montane rainforest. It is a diurnal, stream-breeding species, and used to be found in great concentrations during the reproductive period from July to August (Savage 2002).
This species was formerly abundant but (as of August 2007) it has not been seen since 1986 despite repeated searches; although further searches are needed to finally confirm the exinction of this species. It was formerly abundant on the slopes of Volcán Barva, but is now believed extinct there (Savage 2002).
The major threat is likely to be chytridiomycosis, leading to a catastrophic population decline, as has occurred in many other montane species of Atelopus. Other threats to this species might include climate change, collecting for the pet trade, and possibly pollution.
The range of this species is protected by both Parque Nacional Tapantí and Parque Nacional Braulio Carrillo (although it is now believed extinct in the latter area). Further survey work is required to determine whether or not this species still persists. Given the threat of chytridiomycosis, surviving individuals might need to form the basis for the establishment of an ex-situ population.
Red List Status
Critically Endangered (CR)
Listed as Critically Endangered because of a drastic population decline, estimated to be more than 80% over the last three generations, inferred from the apparent disappearance of most of the population, probably due to chytridiomycosis.
Bolaños, F., Chaves, G. & Barrantes, U. 2008. Atelopus senex. The IUCN Red List of Threatened Species 2008: e.T54549A11165586. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T54549A11165586.en .Downloaded on 19 February 2019