Chiriqui harlequin frog

Poisonous stubfoot toad from Chiriquí Province

The Chiriqui harlequin frog was once widespread in the Cordillera de Talamanca, a mountain range in Costa Rica, and in western Panama. The species was last seen in 1996. The IUCN Red List has listed the frog from the stubfoot toad genus (Atelopus) as extinct since 2019.

Almost all stubfoot toads have strongly shortened inner fingers and toes. Most animals in the genus are colorful and poisonous. The Chiriqui harlequin frog had weakly developed and relatively inconspicuous poison glands distributed across its head and back, but they were still able to produce the powerful neurotoxin tetrodotoxin. Since many animal species (such as pufferfish, some crustaceans, snails, starfish or octopuses) carry the poison tetrodotoxin, researchers assume that these organisms do not produce the toxin themselves, but sequester it from their environment.

The species name Chiriqui is derived from Chiriquí Province, which lies in western Panama on the border with Costa Rica. The Chiriqui harlequin frog once lived in the lower mountain zone of the Cordillera de Talamanca-Chiriquí axis of Costa Rica at 1,800 to 2,500 meters above sea level and in western Panama at 1,400 to 2,100 meters above sea level.

The Chiriqui harlequin frog was diurnal and lived terrestrially along riverbanks in montane cloud forest and rainforest. However, the breeding site and the development of the frog larvae were in forest streams, according to the American herpetologist Jay Savage in The Amphibians and Reptiles of Costa Rica (2002). While the male frogs tended to stay near bodies of water, the females preferred shady places in the forest.

Chiriqui harlequin frog – fact sheet

alternative names	Chiriqui harlequin toad, Lewis’ stubfoot toad
scientific name	Atelopus chiriquiensis
original distribution area	Costa Rica, Panama
time of extinction	1996
causes of extinction	Fungal disease chytridiomycosis, introduced trout, habitat loss
IUCN status	extinct

The Chiriqui harlequin frog was once easy to find

Among others, the herpetologist Erik D. Lindquist stated that the Chiriqui harlequin frog was once abundant in its range. The biologist Frederico Bolaños confirmed this by saying that the species had been very easy to find.

Despite many searches since 2014 in its former range and in other suitable montane habitats, the Chiriqui harlequin frog has not been seen since its disappearance in 1996. Everything indicates that this frog species is indeed extinct.

The chytrid fungus that infects amphibians (Batrachochytrium dendrobatidis) was detected in the Chiriqui harlequin frog in 1993 and 1994. This is reported in the study Chytridiomycosis in Wild Frogs from Southern Costa Rica (2003). The biologist Karen R. Lips and her team link the drastic population decline among Chiriqui harlequin frogs over a five-year period between 1992 and 1996 to chytridiomycosis. It cannot be ruled out that climate change or other factors also played a role in the species’ disappearance.

According to the IUCN, introduced predatory trout may also have eaten more Chiriqui harlequin frog tadpoles and thus contributed to the extinction of the frog species. The extent to which the trout influenced the disappearance of these frogs remains unclear to this day. Habitat loss may also have contributed to the population decline.

Besides the Chiriqui harlequin frog, other amphibian species have also fallen victim to chytridiomycosis, such as the splendid poison frog, Rabb’s fringe-limbed treefrog or the Corquin robber frog.

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