A Czech researcher has captured the first photos and videos of the elusive Subalpine Woolly Rat after it vanished from records for three decades. František Vejmělka's six-month expedition in New Guinea's highlands revealed new details about this massive rodent. The discovery highlights the untapped biodiversity in one of the world's last unexplored regions.
František Vejmělka, a doctoral student from the Biology Centre of the Czech Academy of Sciences and the University of South Bohemia, spent six months trekking through New Guinea's rugged terrain. His efforts culminated in the first scientific observation of Mallomys istapantap, known as the Subalpine Woolly Rat, in its natural habitat. This enormous nocturnal rodent inhabits mist-shrouded forests and grasslands at around 3,700 meters above sea level on Mount Wilhelm, Papua New Guinea's highest peak at 4,509 meters.
First described in 1989 from museum specimens, the species had not been sighted in the wild for 30 years and had never been photographed alive. Vejmělka's work provides the initial images, videos, and biometric data, including measurements of male specimens. The rat measures about 85 cm in total length, including its tail, weighs up to 2 kg, and features 8 cm-long paws, sharp incisors, and dense fur. It is herbivorous, feeding on plant material, and spends nights climbing trees while hiding in burrows or branches by day.
"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?" Vejmělka remarked. He also documented the rat's diet, parasites, movements, and behavior, contributing to knowledge of New Guinea's mammalian diversity. Over the expedition, he identified 61 species of non-flying mammals, including rodents and marsupials.
Vejmělka credits indigenous hunters from local tribes for their guidance in locating the animals. "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," he said. This collaboration underscores the value of blending traditional knowledge with scientific research to protect the region's biodiversity from threats like mining.
The findings appear in the journal Mammalia (2025; 89(4): 376). New Guinean woolly rats, related to Philippine giant cloud rats, have evolved into diverse forms over five million years in the absence of competing placental mammals.