Atelopus varius, the Costa Rican variable harlequin toad or clown frog, is a small Neotropical true toad from the family Bufonidae.[2] Once ranging from Costa Rica to Panama, A. varius is now listed as critically endangered and has been reduced to a single remnant population near Quepos, Costa Rica (rediscovered in 2003), and has only relict populations in western Panama.[1] Recent variation in air temperature, precipitation, stream flow patterns, and the subsequent spread of a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) linked to global climate change have been the leading cause of decline for A. varius.[3][4]A. zeteki has been considered a subspecies of A. varius, but is now generally considered a separate species.[5][page needed]
^Crump, M.L. 1986. "Homing and site fidelity in a Neotropical frog, Atelopus varius (Bufonidae)." Copeia1986(4): 1007–1009. doi:10.2307/1445001JSTOR1445001
^Lips, K.R., Green, D.E. and Papendick, R. 2003. "Chytridiomycosis in wild frogs from southern Costa Rica." Journal of Herpetology37(1): 215–218. JSTOR1565857
^Pounds, J.A., Bustamante, M.R., Coloma, L.A., Consuegra, J.A., Fogden, M.P.L., Foster, P.N., La Marca, E., Masters, K.L., Merino-Viteri, A., Puschendorf, R., Ron, S.R., Sánchez-Azofeifa, G.A., Still, C.J. and Young, B.E. 2006. "Widespread amphibian extinctions from epidemic disease driven by global warming." Nature439: 161–167. doi:10.1038/nature04246
^Savage, J.M. 2002. The Amphibians and Reptiles of Costa Rica. University of Chicago Press, Chicago. ISBN0-226-73537-0