Research, Science & environment

In pursuit of a poison frog — and a culturally appropriate name

UC Berkeley’s Rebecca Tarvin and Colombian colleagues tracked down a new species along that country's Pacific coast, naming it in honor of an Afro-Colombian music style.

By Robert Sanders

brown frog with yellow stripe on side, sitting on a brown leaf — The focus of the 2022 trip: a nondescript, reddish-brown frog about 2/3 of an inch long, with a bright yellow patch at the groin and armpit. Tarvin and colleagues from Colombia wanted to capture specimens to document that this poison frog is a new species, one they named Epipedobates currulao, after an Afro-Colombian music style.
Juan Camilo Ríos-Orjuela

cutouts of 7 small frogs arrayed around map of coastal Colombia — The frog lives in the southern half of the Pacific lowlands of Colombia, part of the Chocó biogeographical region, one of the wettest spots on Earth and home to numerous species of amphibians. Including the newly named species, there are at least three species of Epipedobates living in this region of the Chocó. All seem to sequester toxins in their skin, but are noticeably drabber than other genera of poison frogs that are common in the region.
Photograph of the frog from Timbiquí (Reserva Ranita terribilis, Fundación ProAves de Colombia) was obtained from iNaturalist, photographed by Juan Carlos Luna; other images are by the authors.

two women and a bearded man, all wearing sunglasses, smiling for a selfie aboard a boat — To get to a site where they had seen and collected the frog in 2014 and 2016, the team took a one-hour boat ride along the Pacific coast of Colombia from Buenaventura to the town of Juanchaco, in Valle de Cauca, Colombia. Tarvin (center) is in the boat with Mileidy Betancourth-Cundar (left) and Juan Camilo Ríos Orjuela (right), co-authors of the new paper.
Mileidy Betancourth-Cundar

small boats bobbing in the water alongside a pier, with wispy clouds against a blue sky — Off-boarding on the dock at Juanchaco. Located at the mouth of a bay, Bahia Málaga, Juanchaco experiences very heavy to extremely heavy rainfall year-round — an ideal environment for frogs.
Rebecca D.Tarvin, UC Berkeley

two smiling women on boat with blue sky and blue water behind them — Tarvin first started studying the toxins in the skin of Epipedobates frogs while a graduate student at the University of Texas, Austin, where she met a graduate student from Colombia, Mileidy Betancourth-Cundar, who had a similar interest. Here they are near the beach in Juanchaco in 2022. Betancourth-Cundar, who recently completed her Ph.D. at the University of the Andes in Bogotá, is first author of the paper naming the new poison frog.
Mileidy Betancourth-Cundar

two women standing next to a rusty orange tractor with an attached open-air carriage covered in a blue tarp — Local transport, a passenger tractor, ferried the team from Juanchaco to the nearby village of Ladrilleros, where the hunt would begin.
Juan Camilo Ríos Orjuela

passengers aboard an open air carriage, seen from the rear — A passenger tractor is ideal for transport in the wet and often muddy areas of the Valle de Cauca, Colombia.
Rebecca D. Tarvin, UC Berkeley

green vegetation and brown leaves beside a puddled road — The poison frog is found in fragments of primary forest that once covered this region of the Valle de Cauca but is now reduced to about 10% of its original size. This deforestation alarms biologists because the region has similar biodiversity to that of the Amazon, which itself is undergoing rapid deforestation.
Mileidy Betancourth-Cundar

a smiling woman holding plastic water bottle, perched above a bearded man in hat and glasses — Poison frogs can be difficult to capture by hand because of their toxic skin, diminutive size and coloration. Tarvin, seen here with Camilo Ríos-Orjuela, holds a plastic bottle with one end removed, into which she has coaxed a frog.
Mileidy Betancourth-Cundar

a brown and black frog with a yellow stripe on its side, sitting on a brown leaf — Damp, shaded leaf litter is the frog's preferred habitat. This adult of the new species of poison frog (Epipedobates currulao) was observed in Ladrilleros, Valle de Cauca, Colombia.
Mileidy Betancourth-Cundar

two women bending over dried leaves, using an empty water bottle to probe the leaves — Tarvin and Betancourth-Cundar attempt to capture a frog.
Juan Camilo Ríos Orjuela

a clump of trees and moss-covered log on the edge of a sunny field — The frogs are found in farmland and patches of secondary forest with human-made structures.
Rebecca D. Tarvin, UC Berkeley

discarded white bags amid green leaves, with a tiny frog on one of the bags — Discarded bags once filled with agricultural chemicals are not a deterrent to these frogs, one of which can be seen at the edge of the top bag. "The frogs don't mind as long as it's moist and there's some amount of shade," Tarvin said. "They will even use trash as if it were leaf litter, something they can hide under or lay their eggs on."
Mileidy Betancourth-Cundar

an inflated plastic bag with a small frog and wet leaves inside — Success! Two poison frogs (Epipedobates currulao) collected in Ladrilleros, Colombia.
Rebecca D. Tarvin, UC Berkeley

a moss covered log lies next to a clump of green, leafy plants — A damp log under which the reference animal, or holotype, of Epipedobates currulao was found in Ladrilleros.
Rebecca D. Tarvin, UC Berke

a brown and black frog with a yellow stripe down its side, sitting on a white paper with a tag below, MBC 754 — The reference animal sitting next to its field series number, which stands for Mileidy Betancourth Cundar (MBC), the first author of the paper.
Juan Camilo Ríos Orjuela

3 rows of small frogs, tagged with numbers — Some of the specimens including the holotype (bottom left) prepared for the Museo de Historia Natural C.J. Marinkelle at the Universidad de los Andes in Bogotá, Colombia, and UC Berkeley's Museum of Vertebrate Zoology (MVZ). Tarvin is an MVZ faculty curator for amphibians and reptiles, a collection that contains over 300,000 specimens, including 150 designated holotypes and over 2,000 other type specimens. The MVZ's collections house over 150 years of biological history and are used by researchers examining the geographic and temporal changes in animal populations, species and communities and tracking those patterns in relation to natural or human-induced changes in the environment.
Rebecca D. Tarvin, UC Berkeley

February 10, 2025

La versión en español de este artículo está disponible aquí.

When Rebecca Tarvin was a graduate student studying toxins in the skins of poisonous frogs, she and her colleague Mileidy Betancourth-Cundar collected a frog in Colombia that they suspected was a new species. It differed in coloration from a similar Colombian frog in the genus Epipedobates and had a different mating call.

The trilling call of the newly described species of poison frog, Epipedobates currulao, recorded at Pianguita, Valle del Cauca, Colombia. (Audio credit: Rebecca Tarvin, UC Berkeley)

In 2022, eight years later and a newly appointed assistant professor of integrative biology at the University of California, Berkeley, Tarvin met up with Colombian biologists to collect more of these frogs and confirm a new species. Such “holotype specimens” are necessary to document a new species for posterity. Collecting specimens and identifying new species also helps scientists track the impact of environmental changes and understand the evolutionary origin of traits such as skin toxins, which may one day have medical uses.

Collecting the frogs was easy; they seem to thrive along roadsides and in semiurban areas. But what to name the species? A Colombian colleague played for the team a tape of local marimba-based music called bambuco, and one style, called bambuco viejo, or currulao, stood out. The name Epipedobates currulao seemed appropriate, and with this month’s publication of a paper describing the new species in the journal ZooKeys, it’s now official.

Currulao (koo-roo-LAO), which combines marimbas and drums, is popular in black communities along Colombia’s Pacific coast. Check out a performance on YouTube by Cantadoras del Pacifico at the 2009 Smithsonian Folklife Festival.

“We ended up going with currulao because we liked how it brought in the human perspective,” Tarvin said. “The frog is part of the sound landscape; when they call, it’s part of the background noise in the region. Similarly, currulao is more than just a genre of music. It’s also the cultural practices around the music, the gathering, dancing and the relationship-forming aspects of the experience.”

Tarvin is still investigating the toxins produced by frogs in the genus Epipedobates, which is small, containing about eight species, but is the most recently evolved group of poisonous frogs in South America. By comparing the genetics of these frogs with other poison frog groups, she hopes to understand how their chemical defense technique evolved. Most poisonous animals are brightly colored to advertise their unpalatability, such as the Monarch butterfly’s bright orange color and the gaudy orange, black and blue of poison dart frogs. But Epipedobates frogs are more subtly colored, if not downright drab. Perhaps, she said, bright coloration evolves after the frogs develop their toxic defenses.

The call of E. currulao‘s sister species, E. narinensis, is quite distinct. The recording was made at the Reserva Natural Biotopo in Nariño, Colombia. (Audio credit: Rebecca Tarvin, UC Berkeley)

Epipedobates acquired its chemical defenses more recently than any other group in the poison frog family and shows the largest range in color and defense, Tavin said, but they’re also interesting because of how they acquire their toxicity.

“What’s unique about poison frogs, specifically, is that they sequester toxins from their food, so it’s an entirely different kind of defense that requires an entirely different physiology, compared to venom-producing animals, like snakes and bees,” she said. “Poison frogs eat arthropods that have small amounts of chemicals that can be either toxic or distasteful. And then they accumulate those to levels that become relevant for their own predators.”

Tarvin offers one piece of advice: Because they’re covered in poisons, don’t lick your fingers after picking one up.