Being the smallest tree-kangaroo, this animal is also the largest arboreal mammal, found in Australia, where it most commonly occurs in the rainforest canopy. By its appearance, the Lumholtz’s tree kangaroo greatly differs from other species of tree-kangaroo. The overall coloration of the animal's fur varies from pale grey to black and chestnut. The belly is cream colored, while the fore and hind paws are black. On its face, the animal exhibits a black mask. The kangaroo has 5 digits on each forepaw, equipped with long, curved claws. On each of its hind paws, the animal displays a large fourth digit and medium fifth digit, but lacks hallux; the first and second digits are webbed, having two claws. On all of its paws, the kangaroo has fleshy pads with multiple tuberculations, or papillae, which help the animal grab arboreal surfaces.
These animals are endemic to Northeast Queensland (Australia), distributed from the Daintree River in the north to the southern end of Cardwell Range in the south, from the rainforest/wet sclerophyll forest interface in the west to the ocean coast in the east. Lumholtz’s tree-kangaroos mainly occur at high elevations in upland rainforests, being rarely found in lowland forests. They inhabit microphyll vine forests, complex and simple notophyll vine forests as well as cleared lands.
The Lumholtz’s tree-kangaroo is a non-territorial and solitary animal, usually ignoring conspecifics even in the same tree. Adult individuals are inactive for about 90% of the time, spending 99% of their time in trees. These nocturnal animals are also known to feed and move occasionally by day. The Lumholtz’s tree-kangaroos rest in the canopy, sleeping in a curled position and propped up by multiple branches. They feed in the canopy or middle zone, typically at the edge of the forest, where vines are in abundance. These kangaroos move upon the ground exclusively by bipedal hopping. They are usually nimbler in trees, hopping, moving their limbs both individually and in pairs as well as pulling themselves up with their arms.
These kangaroos have polygynandrous (promiscuous) mating system, where both sexes mate with multiple mates. They mate at any time of year. Males of this species are thought to patrol their territory, which overlaps with these of numerous females, with whom they mate. Usually, a pair forms a brief consort relationship, which last for up to several days. The gestation period lasts for 42 - 48 days, yielding a single baby. The joey lives in the pouch of its mother, beginning to look outside by the age of about 250 days. It first comes out of the pouch at around 300 days of age. After leaving the pouch for good, the young still continues to feed upon maternal milk for 1 - 2 months, remaining within the home range of its mother until up to 650 days of age. Sexual maturity is reached within 4 years in males and 2 years in females.
Potential threats include global warming, which poses a serious danger to the population of this species. In the Atherton Tablelands, the animals have suffered from mass clearing of their rainforest habitat on the fertile basalt soils. Presently, this territory still holds a small, scattered population of these kangaroos, which is threatened by domestic dog attacks as well as road accidents.
According to the IUCN Red List, the total population size of the Lumholtz’s tree-kangaroo is estimated to be 10,000 - 30,000 mature individuals. This species is currently classified as Near Threatened (NT) on the IUCN Red List.