For more than 100 years, a small tropical frog lived unnoticed by science under the wrong name. Although it was widespread, easy to find and familiar to local researchers, the species had never been officially recognized.

A new study has now revealed that Pristimantis milpe is a distinct species, showing how historical museum collections can still uncover unexpected discoveries about Earth’s biodiversity.

A Century-Old Scientific Mystery

Scientists from the Pontifical Catholic University of Ecuador have formally described Pristimantis milpe, also known as the Milpe Robber Frog, after discovering that it had been mistakenly identified for generations.

The breakthrough came from examining preserved frog specimens collected in Ecuador during the 19th century. These historic samples are stored at the Natural History Museum in London, where researchers were able to compare them with modern frog populations from the forests of western Ecuador and southern Colombia.

The investigation revealed that the original specimens had been connected to another species incorrectly. As a result, a frog that had been observed for decades never received its own scientific identity.

The discovery was published in the international scientific journal ZooKeys, which specializes in biodiversity and taxonomy research.

A Widespread Frog With A Hidden Identity

Unlike many newly discovered species that are rare or found only in isolated locations, Pristimantis milpe is surprisingly common. Its known habitat covers more than 67,000 square kilometers across the Chocó forests, stretching from western Ecuador into southern Colombia.

The frog can live in different environments, from areas close to sea level to forests located around 1,200 meters above it. Researchers say that its distinctive nighttime calls make it relatively easy to detect in its natural habitat.

The species belongs to the group commonly known as robber frogs, a diverse family of amphibians found throughout Central and South America. Despite being widespread, it remained scientifically hidden because of the long-standing mistake in classification.

The Nighttime “Clicking” Frog Of The Chocó

The Milpe Robber Frog is most active after dark. Male frogs usually sit on leaves of shrubs and bromeliads several meters above the forest floor, producing loud calls that sound similar to a clicking noise.

The species also shows visible differences between males and females. Females often have brighter colours around their legs and body areas, including orange or light blue tones mixed with dark markings. Males usually have a more consistent and less colourful appearance.

The frog lives in the Chocó region, one of the world’s most biologically diverse forest areas. This ecosystem contains a remarkable variety of plants and animals, making every new discovery important for understanding and protecting local wildlife.

Why Museum Collections Remain Important

The discovery of Pristimantis milpe demonstrates the continuing value of natural history collections. Specimens preserved for decades or even centuries allow modern scientists to return to unanswered questions and review earlier classifications.

In this case, researchers combined old museum material with observations of living frogs in the wild. This approach helped them identify differences that previous scientists had overlooked and confirm that the frog represented a separate species.

Santiago Ron, the lead author of the study, examined the original specimens in London while investigating the classification issue. According to the research team, connecting scientific names with real populations is essential for understanding biodiversity accurately.

New Discoveries Hidden Among Familiar Species

The story of Pristimantis milpe shows that discoveries do not always require exploring unknown places. Sometimes, important findings are hidden in existing collections or overlooked species that have been around for generations.

Scientists believe many questions about Earth’s biodiversity remain unanswered, even among animals that appear familiar. Combining historical research, modern technology and field observations continues to reveal new information about the natural world.

The Milpe Robber Frog is a reminder that even common species can hold scientific surprises — and that museums may still contain discoveries waiting to be found.