Atelopus, commonly known as harlequin frogs, is a large genus of true toads. They live in Central and South America. They go as far north as Costa Rica and as far south as Bolivia. "Atelopus" are small, generally brightly colored and diurnal. Most species live near mid- to high-elevation streams. Many species are now considered endangered, while others already are extinct. The cause of these declines mostly appears to be the chytrid fungus "Batrachochytrium dendrobatidis".