“Lost” giant rat found alive in Papua mountains after 30 years
- Date:
- October 23, 2025
- Source:
- Biology Centre CAS
- Summary:
- In the mist-shrouded mountains of New Guinea, a Czech researcher has achieved a world-first — capturing photos, video, and data of the elusive Subalpine Woolly Rat, Mallomys istapantap. Once known only from museum specimens, this giant, shaggy rodent has been rediscovered after three decades, revealing a hidden ecosystem of biodiversity. Working alongside indigenous hunters, the expedition not only unveiled new scientific insights but also strengthened the bridge between local knowledge and modern research — offering hope for conservation in one of the planet’s last unexplored frontiers.
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After spending six months exploring the rugged landscapes of New Guinea, a young Czech doctoral student from the Biology Centre of the Czech Academy of Sciences and the University of South Bohemia has made an extraordinary find. František Vejmělka is the first researcher to observe and scientifically documentMallomys istapantap in its natural environment. This enormous nocturnal rodent, one of the largest in the world, lives high in the cool, mist-covered forests and grasslands around 3,700 meters above sea level. Until now, scientists knew the species only from a few preserved museum specimens. For the first time, photographs and video footage now reveal the animal alive in its native mountain habitat.
Bringing a Lost Species Back Into View
The Subalpine Woolly Rat (Mallomys istapantap) was first identified in 1989 from museum samples and had not been recorded in the wild for three decades. It had never been photographed until now. The new field data and imagery collected by Vejmělka provide crucial insight into this rarely seen species and shed new light on the extraordinary mammalian biodiversity of New Guinea's remote highlands.
A Mysterious Giant of the Highlands
"It's astonishing that such a large and striking animal has remained so poorly studied. How much more is there to discover about the biodiversity of tropical mountains?" says Vejmělka. Alongside the groundbreaking photos and videos, he obtained the first biometric measurements of male specimens and documented details about the animal's diet, parasites, movements, and daily behavior.
New Guinean woolly rats, related to the giant cloud rats of the Philippines, rank among the largest murine rodents on Earth. They live only in the steep, rainforest-covered highlands of New Guinea. In the absence of other competing placental mammals, these rodents have diversified over roughly five million years into a surprising array of distinct forms and species.
Life of the Subalpine Woolly Rat
The thick-furredMallomys istapantap leads a secretive life in isolated, high-altitude regions. Active at night, it climbs trees in search of food and takes shelter during the day in burrows or among tree branches. Feeding exclusively on plant material, it has sharp incisors, dense fur, 8 cm-long paws, and a total body length (including tail) of about 85 cm. Weighing up to 2 kg, it is both imposing and elusive. Its nocturnal behavior and inaccessible habitat have made direct observation extremely rare.
Science Meets Traditional Knowledge
"If it weren't for the indigenous hunters who accompanied me in the mountains and helped me locate the animals, I would never have been able to collect this data," says Vejmělka. During his six-month expedition, he worked closely with several local tribes while surveying the mammalian diversity of Mount Wilhelm (4,509 m), the highest peak in Papua New Guinea, from base to summit. He documented and genetically identified 61 species of non-flying mammals (rodents and marsupials) found along the mountain.
This fieldwork deepens scientific knowledge of the incredible but still underexplored wildlife of New Guinea's tropical mountains. While similar habitats in regions such as the Americas, Africa, and Southeast Asia have been studied extensively, the Australasian highlands remain far less known. Collaboration with local communities is a vital part of this progress.
Through these shared research efforts, indigenous groups gain awareness of their region's unique natural heritage and the importance of protecting it from increasing threats, including mining.
The findings have been published in the scientific journalMammalia.
Story Source:
Materials provided byBiology Centre CAS.Note: Content may be edited for style and length.
Journal Reference:
- František Vejmělka.First scientific observation of the largest Sahulian rodent, Mallomys istapantap, in the wild.Mammalia, 2025; 89 (4): 376 DOI:10.1515/mammalia-2024-0153
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