The world always needs more rats (doesn´t it?) and so you will pleased to know that a new one has been discovered! Drymoreomys albimaculatus is orange, hairy and lives in trees.
Actually, Drymoreomys albimaculatus are very, very, rare, even one of the authors of the paper describing them had never seen a live one. They live on the eastern slopes of the Serra do Mar, in the coastal Brazilian Atlantic rainforest from São Paulo down to Santa Catarina, at altitudes of 650 to 1200m. Which means cold damp forest with winter temperatures down to below 0 C, which is probably why they have unusually long thick fur. Although all the ones that have been caught were on the ground, they probably climb trees as they have long prehensile tails and special pads on the palms of their paws for climbing.
Drymoreomys means forest mountain rat, and albimaculatus refers to the white spots they have in their orange pelt. And that's about it. Their life cycle, predators, place in the ecosystem is a mystery. Goodness knows what they eat, probably everything, rats aren´t usually fussy.