An Australian-led expedition says it has discovered three new mammal species in Papua New Guinea, releasing for the first time a picture of one of the animals – a diminutive wallaby – to Guardian Australia.



More than 40 camera traps were set up in two little-studied mountains in the remote Torricelli range, in north-east Papua New Guinea, during the four-month study.



The Docopsulus wallaby, a small marsupial, was captured on camera, as well as a “Dumbo” mouse with giant ears, and an antechinus, a sort of shrew-like marsupial.



Euan Ritchie, an ecologist at Deakin University in Melbourne, partnered with the Tenkile Conservation Alliance, a group headed by Australians Jim and Jean Thomas which is dedicated to protecting tree kangaroos, for the project.

The study resulted in several rare tree kangaroos being photographed, as well as the three species which appear to be new to science.

Ritchie said the wallaby, of which Guardian Australia has obtained a picture, is about the size of a domesticated cat.

“There are not that many truly small macropods, so it’s quite unusual,” he said. “But we don’t know much about their diet or behaviour, or how many they are. This is all very much frontier stuff.”

Ritchie said a further expedition will look to capture the new species and take DNA samples to verify the findings.

“The feeling is better than Christmas,” he said. “To go somewhere no one has gone before in order to describe new animals is pretty fantastic.

“It will be tricky to capture the animals but we’d hope we can turn the locals’ hunting skills to good in order to trap them.”

The camera traps revealed a number of rare other animals, including the Tenkile tree kangaroo and the Weimang tree kangaroo, which are thought to number just 600 individuals between them.

Other images taken include the dwarf cassowary, the grizzled tree kangaroo and the hooded pitohui, the only poisonous bird in the world.

Ritchie said the findings would be used to press the Papua New Guinea government to ensure the mountain range is protected. Until now, the range has been largely undisturbed by mining or logging, although hunting of tree kangaroos by locals posed a serious threat to the animals until the work of the Tenkile Conservation Alliance helped reverse the species’ fortunes.

The remote mountains could house “hundreds” of other species not known to science, says Ritchie.

“We were only looking for mammals, but if you think of plants, insects and reptiles, there are likely to be a large number of new species,” he said. “This is a large area of rainforest and we want to make it a lifelong pursuit to discover new species.

“It’s exciting, but at the same time we have a massive biodiversity extinction crisis at the moment and the sad thing is that we lose many species before we even know they exist.”