A frog seen for a century across two countries finally got a name of its own

A frog that has been calling from leaves across two South American countries for well over a century finally has an official name to match its familiar face. Scientists tracing the mix-up back to museum drawers in London have determined that a widespread, commonly seen amphibian in Ecuador and Colombia was never actually classified correctly in the first place.

Pristimantis milpe Steps Out of the Shadows

Researchers at the Pontificia Universidad Católica del Ecuador have formally described Pristimantis milpe, a frog whose known range covers more than 67,000 square kilometers across the Chocó forests of western Ecuador and southern Colombia, from sea level up to elevations of 1,200 meters. What sets this discovery apart from many new-species announcements is that Pristimantis milpe is neither rare nor confined to a remote patch of forest. It is common, easy to find, and readily detected at night by its distinctive call, meaning generations of biologists, hikers, and local residents have almost certainly encountered it without realizing it lacked a scientific name of its own. The formal description appears in the taxonomy journal ZooKeys.

A Mystery Solved With 19th-Century Museum Specimens

The breakthrough came from revisiting history rather than fieldwork alone. Santiago Ron, a researcher at PUCE and the study’s lead author, traveled to London to examine amphibian “type” specimens collected in Ecuador during the 1800s and preserved ever since at the Natural History Museum. By comparing those historical specimens against living frog populations in the Ecuadorian Chocó, Ron’s team discovered that the old museum specimens had been incorrectly linked to a different, already-named species for more than a century. That misidentification meant a frog regularly observed and documented in the wild for decades never received a name that actually matched its biology. “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,” said Jhael Ortega, a PhD student at Virginia Tech and one of the study’s co-authors.

The Clicking Frog of the Chocó

Known locally as the Milpe Robber Frog, or Cutín de Milpe, Pristimantis milpe is active after dark, when males call from leaves on shrubs and bromeliads several meters above the forest floor. Their calls are loud and distinctive, producing a sound researchers describe as similar to a click, which likely explains why the species has been so consistently noticed even while its taxonomy remained unresolved. The frog also displays clear differences between the sexes: females carry striking orange or light-blue coloration mixed with black spots around the groin and thighs, while males tend toward more uniform coloring. The species inhabits a region considered a global priority for biodiversity conservation, and researchers note it has also been observed in banana plantations and urban parks, suggesting a degree of adaptability to human-altered landscapes. That adaptability likely helped the frog persist, and even thrive, in areas where agriculture and urban expansion have reshaped much of the surrounding forest, even as its formal identity remained unresolved.

Why Old Museum Collections Still Matter

The case underscores a point taxonomists have long made: natural history collections are not simply archives of the past but active tools for solving present-day biological puzzles. Specimens preserved for a century or more can be revisited with modern techniques and comparative data that earlier generations of scientists simply did not have access to. In this instance, combining 19th-century museum material with observations of living populations allowed Ron’s team to determine, definitively, that Pristimantis milpe deserved recognition as its own distinct species rather than remaining folded into another animal’s name. The resolution also required untangling a related synonymy involving Pristimantis subsigillatus, the species with which the Chocó frog had been historically confused. Sorting out that tangle meant carefully comparing physical traits across multiple museum specimens and modern field samples, a painstaking process that can take years even once researchers suspect something is amiss with an existing classification.

A Reminder of How Much Remains Undocumented

Beyond the specific taxonomic fix, the discovery is a reminder of how much biodiversity remains poorly documented even in well-studied regions and even among common, easily observed species. If a frog this widespread and vocal could go without a proper scientific name for over a hundred years, researchers say it raises questions about how many other overlooked classification errors may be hiding in plain sight across the world’s most biodiverse regions. For now, Pristimantis milpe joins the growing catalog of Ecuadorian and Colombian amphibians with an identity that finally matches its biology, closing a century-long case of mistaken identity that began not in a rainforest, but in a museum drawer thousands of miles away.

This article was created with the assistance of AI and reviewed by an editor.

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