27-05-2025
A Mysterious Rat Vanished Into the Mountains in 1989. It Just Showed Its Face for the First Time Since.
Here's what you'll learn about when you read this story.
Mallomys istapantap is the largest (and also least studied) species of woolly rat in New Guinea, and it has finally been documented in photos and on video.
This species was first documented in 1989, but in their attempts to further study the creature, researchers had little to go off of other than a handful of museum specimens.
The knowledge preserved by local Indigenous people suggests that only sightings of the M. istapantap by scientists—and not the species itself—are rare.
Not all rats are sewer or subway denizens skittering away with someone's slice of pizza (and then going viral for it). In the remote mountain rainforests of Papua New Guinea, there is a creature that has managed to elude humans for decades—a giant rat that hides in the leafy shadows and has never known a discarded pizza crust.
Meet Mallomys istapantap, the Subalpine Woolly Rat of New Guinea. This behemoth of a rodent can easily grow to be the size of a house cat and reach lengths of 85 centimeters (or 33 inches). Several different species of woolly rat have been found in the region, but M. istapantap is easily the largest, and the least studied. It is also one of the largest rodents in the world, next to species such as pacarenas and capybaras. Now, zoologist František Vejmělka has become the first to document this mysterious nocturnal rodent in the wild, catching the creature on both photo and video as it scurries down a tree branch at just past sunset.
'It seems that the rarity of the Subalpine Woolly Rat in museum collections and the limited knowledge on its ecology do not reflect its true rarity in nature, but are rather connected only to the remoteness of the habitats it occupies and to the fact that it cannot be recorded by standard methods of small rodent trapping,' Vejmělka said in a study recently published in the journal Mammalia.
Isolated island habitats can lead to the evolution of some exotic and unusual fauna. Along with outsize rats, New Guinea is home to birds of paradise, iridescent snakes, fanged frogs, grunting fish, tree kangaroos, and several rare species of echidna that exist nowhere else on Earth. Mallomys is a whole genus endemic to the island, and consists of four species of woolly rat. The other species have slightly better documentation, but M. istapantap was first described in 1989 and only visually documented through an illustration in 1995. Until now, the only way to study it up close has been through a handful of museum specimens.
M. istapantap is an herbivore that eats mostly ferns and lives in mossy forests or grasslands near the mountains. It is mostly terrestrial—though still able to climb trees if it needs to escape predators—and its thick and shaggy fur keeps it from feeling the chill of high elevations. The species name 'istapantap' is Melanesian Pidgin (spoken by the local Indigenous people) and means 'living above' or 'it is on the top.' This knowledge of the creature's existence shows that it is probably glimpsed regularly among the roots and leaves by locals. Hunters who helped Vejmělka collect samples seemed to know areas where he was most likely to find M. istapantap, though population numbers are still unknown.
In addition to having local hunters as his guides, Vejmělka set up a camera trap on a fallen log over a stream in a dense forest on Mount Wilhelm—the highest mountain in New Guinea. The camera ran for eight nights until a male M. istapantap, eyes shining in the darkness, was filmed crawling across the log.
Woolly rat species that live in lower elevations have longer tails, while those in higher elevations have shorter tails—an axiom that also applies to the white-tipped tail of M. istapantap. They have dark, brownish-grayish fur with white undersides and pale feet, and females are slightly larger than males. Vejmělka also discovered a color variation never seen before in the species (or any rodent species in the Hydromyini group of rodents, for that matter), which features a streak of yellow on the chest that he thinks is either genetic or staining from sebaceous glands. (This might be related to territorial behavior.)
'The results presented here show primarily the persisting importance of conducting field expeditions in the present, particularly to understudied regions of the Earth,' said Vejmělka. 'The combination of modern and traditional detection methods […] resulted in the first specimen records of this remarkable rodent in over 30 years.'
You Might Also Like
The Do's and Don'ts of Using Painter's Tape
The Best Portable BBQ Grills for Cooking Anywhere
Can a Smart Watch Prolong Your Life?
