František Vejmělka, a doctoral student at the Biology Center of the Czech Academy of Sciences and the University of South Bohemia, made a major breakthrough after a six-month field trip to New Guinea. He became the first scientist in the world to observe and record one of the largest rodents on earth - Istapantap hairy mouse (Mallomys istapantap) in the wild.
Mallomys istapantap. An infrared camera captures images. Image source: František Vejmělka, original article published in: Vejmělka, F. (2025)
This mysterious and nocturnal animal only inhabits cool mountain forests and grasslands at an altitude of about 3,700 meters. Previously, scientific knowledge of it was limited to a handful of museum specimens. No living body has ever been photographed or videoed in the wild. František Vejmělka completed the first video recording of this species in its natural environment.
The Istapantap hairy-footed mouse was first identified in 1989 based on historical museum collections. In the past 30 years, there have been only sporadic confirmation records and no imaging data. The new photos and ecological data collected this time provide important progress in understanding this rare species and enrich our understanding of the diversity of New Guinea mammals.
"It's shocking that such a large and distinctive animal is so little known. How much of tropical mountain biodiversity is still undiscovered?" Vejmělka said. In addition to photos and videos, he also recorded male biometric data for the first time and collected information on the animals' feeding habits, parasites, activity patterns, movement patterns and other living habits.
The hairy-footed rat of New Guinea and the giant cloud rat native to the Philippines together make up the largest rodents in the world. They are highly dependent on the steep alpine terrain of New Guinea and have evolved over five million years to develop a variety of unique species and forms in the absence of competition from other placental mammals.
The Istapantap hairy-footed mouse has thick fur, sharp incisors, 8 cm long claws, a body length of about 85 cm (including tail) and a weight of nearly 2 kg, making it a mouse with outstanding strength and size. However, due to its nocturnal nature and remote habitat, it is extremely difficult for humans to see its true appearance. They climb branches to feed at night and hide in burrows or canopies during the day.
“I wouldn’t have been able to collect this information without the help of indigenous mountain hunters,” Vejmělka said. During the six-month expedition, he worked closely with several tribes to comprehensively investigate the diversity of mammals from the foot to the top of Mount William (4,509 meters), the highest peak in Papua New Guinea. A total of 61 species of non-flying mammals (including rodents and marsupials) were recorded and genetically identified.
This research not only deepens our understanding of the extreme diversity of New Guinea's tropical high mountains, but also highlights the importance of collaboration with local communities. Compared with the rich research on tropical regions of the Americas, Africa and Southeast Asia, there are still many gaps to explore in the Australian and New Zealand bioregions. Through scientific work, indigenous peoples also understand and realize their unique natural heritage and the significance of conservation, such as responding to new threats such as mining.