Scientists from the Pontificia Universidad Católica del Ecuador officially described Pristimantis milpe, an abundant and widely distributed species that had been confused with another species for over a century. To solve the mystery, researchers reviewed specimens collected in Ecuador during the 19th century and preserved at the Natural History Museum in London.

The finding is exceptional because, unlike many recently described species – which are usually rare or restricted to small geographic areas – Pristimantis milpe is a common frog, widely distributed, and easy to detect by its nocturnal call. The species inhabits the Chocó forests of western Ecuador and southern Colombia, in a range that exceeds 67,000 square kilometers, from sea level up to 1,200 meters in altitude.

The scientific description was published in the international journal ZooKeys, which specialises in research on biodiversity and taxonomy.

The identification of Pristimantis milpe was made possible thanks to a review of the historical amphibian collections preserved at the Natural History Museum in London (NHM).

To resolve a taxonomic confusion that lasted for more than a century, Santiago Ron, a researcher at PUCE and lead author of the study, travelled to England to examine the original specimens – known as “types” – that were collected in Ecuador during the 19th century and preserved ever since.

The analysis allowed these historical specimens to be compared with current populations of frogs from the Ecuadorian Chocó. The researchers determined that the specimens had been erroneously associated with another species. This confusion caused a species that had been present and observed for decades to remain without a scientific name of its own.

“That such a common species has gone unnoticed under the wrong name for decades highlights the importance of correctly connecting scientific names with living populations in nature,” notes Jhael Ortega, a PhD student at Virginia Tech and one of the study authors.

The Milpe Robber Frog (Cutín de Milpe) is a species with nocturnal habits. Males usually call from the leaves of shrubs and bromeliads located several meters high within the forest. Their vocalisation is characterized by a loud and distinct sound, similar to a “click.”

One of its most striking features is the dimorphism between females and males. Females present a distinctive color pattern on the groin and thighs, with orange or light blue tones accompanied by black spots. Males, on the other hand, have more uniform shades.

The species is found in the forests of the Ecuadorian Chocó and southern Colombia, one of the most important regions for biodiversity conservation.

The study demonstrates the scientific value of natural history collections. Specimens preserved for centuries allow current researchers to review classifications, compare characteristics, and answer questions that remained open for generations. In this case, the analysis of specimens collected in the 19th century, combined with the study of current populations, allowed Pristimantis milpe to be formally recognised as a distinct species.

The work also shows that biodiversity still holds surprises even in abundant and well-known species, and that scientific research requires connecting historical knowledge with the tools and observations available today.

Ron SR, Paredes-Aguirre P, Paucar DA, López Y, Apunte K, Ortega JA (2026) Long overdue: a new, widespread, species of Pristimantis (Anura, Strabomantidae) from the Chocó region and the synonymy of Pristimantis subsigillatus. ZooKeys 1286: 121-152. https://doi.org/10.3897/zookeys.1286.194383