Specimens that have languished in the collection of London’s Natural History Museum since the 19th century have recently revealed a major new species discovery.
Researchers from the Pontificia Universidad Católica del Ecuador described the new frog species, Pristimantis milpe, also known as the Milpe Robber Frog, in a recent paper published in ZooKeys.
The find is notable because it is a relatively widespread species, rather than a small insect or one relegated to a tiny ecological niche. Additionally, it is a species that locals have commonly known for decades, although it had long been misidentified since it was collected in Ecuador years ago, and was only recently rediscovered by scientists from that country during a visit to the UK.
Discoveries Hidden in Museum Collections
Stories of overlooked specimens languishing in museum collections for decades are surprisingly common. But such discoveries often involve obscure organisms known from only a handful of specimens or species that disappeared millions of years ago. What makes this case unusual is that the animal in question was never particularly difficult to find—it had simply been hiding in plain sight under the wrong name.
Pristimantis milpe is a common frog, inhabiting an estimated 67,000 square kilometers of the Chocó forests of western Ecuador and southern Colombia, from sea level to elevations of roughly 1,200 meters.
In this region, the frog is well known to locals, with a distinctive nocturnal call that makes it stand out amid the sounds of the forest. Yet despite these factors, specimens held by the Natural History Museum were mistakenly cataloged as another species.
A Discovery, and a Mistake
The study’s lead author, Santiago Ron, traveled to London to examine Ecuadorian specimens during a review of the institution’s historical amphibian collections. While comparing these historical specimens with present-day tree frog species from the Ecuadorian Chocó, Ron discovered that two distinct species had been mistakenly conflated.
Because of this error, a species commonly known in the region for decades had never been officially cataloged, named, or recognized by science.
“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,” commented co-author Jhael Ortega, a PhD student at Virginia Tech.
A Distinct Frog Species Emerges
Locals know the Milpe Robber Frog is nearby because of the loud clicking sound it makes in the nighttime forest. It also has distinctive habits, usually perching on shrub leaves or bromeliads as it calls into the surrounding forest.
Although it is a nocturnal creature, the frog is also known for its striking coloration, which differs between the sexes. Male Milpe Robber Frogs tend to have more uniform coloration, while females have blue coloring with black spots on their groin and thighs.
The Ecuadorian Chocó is an important area for wildlife conservation because of its extraordinary biodiversity, as this discovery attests. Between 1938 and 1988, more than 90% of the region’s forests were cut down, primarily to make way for banana plantations.
Careful preservation of this region, along with the collections housed in institutions like the Natural History Museum, will be essential for further probing that biodiversity in the future. If a species this widespread is only now being formally recognized by science, it raises a fascinating question: What else might still be hiding in plain sight in South America’s forests—and in museum collections around the world?
The paper, “Long Overdue: a New, Widespread, Species of Pristimantis (Anura, Strabomantidae) from the Chocó Region and the Synonymy of Pristimantis Subsigillatus,” appeared in ZooKeys on July 24, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.