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.

 

Since 2004 scientists have continued to survey additional areas for A. varius and other lost frogs, resulting in finding a handful of individuals in Panama. In Costa Rica, ongoing surveys resulted in the 2008 discovery reported here.

 

Jan Schipper, director of Sierra to Sea Institute and an adjunct professor at Arizona State University, reports that the presence of harlequin frogs in Costa Rica contradicts expectations. Given the typical catastrophic impact of chytrid fungus, "This population shouldn't be here. It provides hope that there are other populations surviving in other areas," he says.

 

The next steps will be to pull together resources to implement a long-term monitoring and recovery program for the species. Ensuring its survival against many odds will be a difficult task.