A species of fork-marked lemur believed to be new to science has been found in the forests of Madagascar.
The find is revealed on the BBC documentary Decade of Discovery.
Primate expert and president of Conservation International, Russ Mittermeier, first spotted the lemur during an expedition in 1995, but has confirmed its existence whilst filming the documentary this year, when he and his colleagues captured and took blood samples from the small primate before returning it to its forest home.
I immediately knew that it was likely a new species to science
Genetic testing of these samples should confirm whether the animal is indeed a new species.
Dr Mittermeier, however, is already convinced that it is.
Forked-marked lemurs belong to the genus, or group of species, called Phaner. If confirmed as a new species, this would be only the fifth member of that group.
Following the call
Dr Mittermeier first saw the squirrel-sized creature in Daraina, a protected area in the northeast of Madagascar.
He was there in search of another lemur - the golden-crowned Tattersall's sifaka (Propithecus tattersali), a much larger species only discovered in 1988.
"I was surprised to see a fork-marked lemur there, since this animal had not yet been recorded from the region," he recalled.
Phaner lemurs have a black, Y-shaped line that starts above each eye and joins together as a single line on the top of the head, creating the fork that gives these animals their common name
Their large hands and feet help them grip onto trees
The lemurs vocalise with the loud, high-pitched night-time call
They tend to run rapidly along horizontal tree branches and to jump from one branch to the next without pausing
Their diet consists of a high proportion of gums exuded by trees and nectar from flowers
A long tongue enables them to slurp up nectar and a specialised toothcomb acts as a scraping tool to bite into tree bark
"I immediately knew that it was likely a new species to science, but didn't have the time to follow up until now."
So in October of this year, the researcher led an expedition - including geneticist Ed Louis from the Omaha Zoo and a film crew from the BBC's Natural History Unit - to the same area, where they managed to track down the animal.
The team set out just after sunset, which is when fork-marked lemurs are most vocal.
They heard one calling close to camp at the top of a tree and ran through the forest following its calls.
The researchers eventually caught sight of the animal in the torchlight, and fired a tranquiliser dart.
A team member then climbed the tree to bring the sleepy little lemur safely down to the ground, where they could examine it.
The shape of the lemur's markings, the size of its limbs and its long, nectar-slurping tongue are familiar facets of all Phaner lemurs.
But this one has a slightly different colour pattern. It also displayed an unusual head-bobbing behaviour that the scientists had not seen in other fork-marked lemurs.
A strange structure under the lemur's tongue could also distinguish it from its closest relatives.
"The genetics will tell the real story," said Dr Mittermeier.
If confirmed as a new species, Dr Louis and Dr Mittermeier would like the animal to be named after Fanamby, the conservation organisation that has been instrumental in protecting the forest of Daraina.
New to science
"This is yet another remarkable discovery from the island of Madagascar, the world's highest priority biodiversity hotspot and one of the most extraordinary places in our planet," Dr Mittermeier said.
"It is particularly remarkable that we continue to find new species of lemurs and many other plants and animals in this heavily impacted country, which has already lost 90% or more of its original vegetation."
And because of its very restricted range, it is likely that this will turn out to be an endangered or critically endangered species.
Decade of Discovery, a collaboration between Conservation International and the BBC's Natural History Unit, will be broadcast at 20.00BST on Tuesday 14 December on BBC Two.