Scientists have discovered something small and remarkable: a new species of marsupial with a natural “mask” high in the Andean cloud forests of northern Peru. The animal, known as Marmosa chachapoya, was found in Rio Abiseo National Park, a reference to the Chachapoya people who once inhabited these mountains before the Inca Empire.
In order to demonstrate that this is a genuinely new species, the study, which was headed by biologist Silvia Pavan and published in American Museum Novitates, used DNA and anatomy. The creature is thin, small (about 10 cm in length), coppery on the belly, and has dark fur bands covering its face that look like eye masks. And the only known specimen’s home is in the the National University of San Marcos (Lima).
That one animal is already changing our understanding of the Andes’ fauna and the many mysteries that are still hidden in UNESCO protected areas. One of the most diverse lineages of American marsupials, the genus Marmosa, now has a bigger membership thanks to the discovery.
A tiny neighbor in the cloud forest
The story began in 2018. In Rio Abiseo National Park, a research team hiked to a location known as La Playa, which is more than 2,600 meters above sea level. In fact, they were searching for evidence of a mysterious squirrel that had been spotted nearby. But actually, a tiny marsupial fell into a sampling trap.
It didn’t look familiar at first. But once back in the lab, the team sequenced nuclear and mitochondrial DNA and compared the animal to dozens of specimens from the museum.
The findings were clear that this species was new to the genus Marmosa, specifically to the Stegomarmosa subgroup (previously known for M. lepida and M. andersoni). The animal possessed distinct physical characteristics in addition to genetic divergence, like a longer, narrower snout than its relatives, a skull devoid of postorbital processes, and tiny spaces between canines and premolars.
These variations are the kind of hints that show how evolution shapes species in harsh environments that are difficult to reach. The Chachapoya culture, sometimes called the “warriors of the clouds,” whose historic highest locations still give a view of these forests, is honored by the name Marmosa chachapoya.
Science, culture, and conservation
The rich biodiversity and archaeological treasures that Rio Abiseo National Park preserves make it a UNESCO World Heritage Site. The presence of Marmosa chachapoya there reminds that protecting natural areas saves more than just the landscape; it also saves species and stories.
And the science is fascinating. The Andes are well-known for their “islands” of habitat, which include steep slopes, misty forests, and deep canyons that isolate populations. Researchers have reported new rodents, amphibians, and reptiles in the park in recent years. They believe there may be an odd semi-aquatic rodent that hasn’t been given a name yet.
Marmosa’s chachapoya’s diet, daily activities, social behavior, and true range are still unknown because all of the information we have about it comes from a single young adult specimen discovered in 2018. The lack of new specimens could suggest that it is very rare or just hard to find. It may only be found in a small area of cloud forest or along the eastern slope of the Andes, between the Marañón and Huallaga rivers.
Big lessons from a small mammal
The Andes continue to be mysterious, as demonstrated by Marmosa Chachapoya. There is still more to discover to be done. Together, biology, genetics, fieldwork, museum science, and conservation reveal new parts of the puzzle of life.
The goal of protecting these cloud forests and continue the research. If a marsupial has been hidden until now, what else is there?