The knowledge preserved by local Indigenous people suggests that only sightings of the M. istapantap by scientists—and not the species itself—are rare. Several different species of woolly rat have been found in the region, but M. istapantap is easily the largest, and the least studied. Mallomys is a whole genus endemic to the island, and consists of four species of woolly rat. M. istapantap is an herbivore that eats mostly ferns and lives in mossy forests or grasslands near the mountains. The camera ran for eight nights until a male M. istapantap, eyes shining in the darkness, was filmed crawling across the log.