The critically endangered harlequin frog (Atelopus varius), believed to be extinct in Costa Rica, has been rediscovered in the Talamanca Mountains of southern Costa Rica by an international team of researchers. The harlequin frog was a relatively common species in areas of Costa Rica and Panama until 1988, when populations declined rapidly, primarily as a result of the invasive, infectious chytrid fungus (implicated in extinctions of hundreds of amphibian species globally). The increasingly rare harlequin was believed extirpated from Costa Rica until 2004, when two individual harlequin frogs were spotted in a remote area near Manuel Antonio National Park in the western region of the country. Unfortunately, no harlequin frogs have been seen at this location since then.