Atelopus varius (Lichtenstein & Martens, 1856)

Common Name and Classification

Atelopus varius, commonly known as the Costa Rican variable harlequin toad or clown frog, is a small Neotropical true toad in the family Bufonidae.

Conservation Status

While this species historically ranged from Costa Rica to Panama, it is currently classified as critically endangered.

Its populations have been reduced to a single remnant group near Quepos, Costa Rica (rediscovered in 2003), plus only relict populations in western Panama.

Population Decline Causes

The leading causes of A. varius population decline are recent changes in air temperature, precipitation, and stream flow patterns, as well as the resulting spread of the pathogenic chytrid fungus Batrachochytrium dendrobatidis, changes linked to global climate change.

Taxonomic History

A. zeteki was once classified as a subspecies of A. varius, but it is now generally recognized as a separate species.

Historic Geographic Range

The historic geographic range of A. varius extended from the Pacific and Atlantic slopes of Costa Rica's Cordilleras de Tilaran mountain range into western Panama.

Suitable Habitat and Elevation

Suitable habitat for the species includes pre-montane, lower-montane, and some lowland sites along rocky streams in hilly areas, at elevations ranging from 6 to 2,000 metres (20 to 6,562 feet).

Activity Period and Microhabitat

A. varius is a diurnal species, often found on rocks or in crevices alongside streams in humid lowland and montane forests.

Terrestrial Behavior and Moisture Source

It is primarily terrestrial, only entering water during breeding season, and gets the moisture it needs from stream spray.

Movement and Site Fidelity

The Costa Rican variable harlequin frog moves slowly and often stays in the same area for long periods of time.

Coloration and Defense Mechanism

Its conspicuous aposematic coloration likely acts as a warning to potential predators that its skin contains tetrodotoxin, a potent neurotoxin.

Diet

The main food source of A. varius is small arthropods, which are most abundant during the dry season.

Known Predator

The only known predator of A. varius is the parasitic sarcophagid fly Notochaeta bufonivora, which deposits its larvae on the surface of the frog's thigh.

Parasitic Larvae Behavior

The larvae then burrow into the frog's body and eat it from the inside out.