Centuries‑old specimens uncover a distinct Andean frog species

A team of herpetologists has confirmed that a frog long thought to belong to a widespread species is in fact a distinct taxon, now named Pristimantis milpe. The amphibian inhabits the montane forests of Ecuador and Colombia and has evaded recognition as a separate species for more than a hundred years. The finding, published this month, underscores how even well‑collected groups of animals can conceal hidden diversity that only modern analysis can reveal.

The frog was originally lumped with a common Pristimantis species that populates the Andean foothills. Field observations over decades noted subtle variations in coloration and call structure, but those differences were dismissed as regional variation. Because the animal is small, nocturnal and lives in leaf litter, it rarely stands out, allowing the misidentification to persist throughout the 20th century.

Researchers turned to historical collections, examining specimens gathered by European naturalists in the late 1800s. By comparing the morphology of those museum skins with fresh material, and by sequencing DNA from both old and new samples, they identified consistent differences in skeletal proportions, skin texture, and genetic markers. The older specimens, some dating back more than 130 years, provided the baseline that clarified the frog’s unique identity. This integrative approach—combining classic taxonomy with molecular data—proved decisive in separating Pristimantis milpe from its look‑alike relatives.

Recognizing Pristimantis milpe as a distinct species carries practical implications for conservation. The frog’s range overlaps with areas experiencing rapid deforestation and agricultural expansion, yet its status had never been assessed independently. With a formal name and diagnostic description, conservation agencies can now evaluate its vulnerability and prioritize habitat protection where the species occurs, potentially adding a new focal point for amphibian preservation in the northern Andes.

The case also highlights a broader pattern in tropical biology: many organisms described only from a handful of specimens may hide unrecognized lineages. As museum collections are digitized and genetic tools become more accessible, scientists expect similar revisions across other amphibian groups. The discovery of Pristimantis milpe serves as a reminder that historical archives remain a vital resource for uncovering biodiversity that modern surveys alone might miss.

Future work will aim to map the precise distribution of the newly defined species, monitor its population trends, and investigate its ecological role within the leaf‑litter community. By clarifying the taxonomy, researchers have laid the groundwork for targeted studies that could inform both science and policy, ensuring that this once‑overlooked frog receives the attention needed to survive in a changing landscape.