The most species-rich genus of the long-tailed monkey and colobus monkey, the crested langur, lives in the forests of Southeast Asia. In order to reconstruct the evolutionary history and the relationships of this group of monkeys, researchers have now analyzed the genetic material from numerous fecal samples as well as from museum specimens. In doing so, they came across a new species not previously described: the Popa langur. It lives in central Myanmar and differs from related species not only genetically, but also in coat color, tail length and skull size. Due to the loss of habitat and illegal hunting, the Popa langur is seriously threatened with extinction.
Crested langurs live in the tropical rainforests and open mountain forests of Southeast Asia. The narrow-built monkeys with long tails are around 40 to 80 centimeters tall, depending on the species, and can weigh 5 to 15 kilograms. So far, 20 species of crested langurs are recognized, divided into four groups: the Pileatus group, the Francoisi group, the Cristatus group and the Obscurus group. One of the most widespread and at the same time least studied species is the Phayre’s long-eared langur (Trachypithecus phayrei), a member of the Obscurus group.
DNA from fecal samples and museum specimens
A team led by Christian Roos from the German Primate Center (DPZ) in Göttingen and Frank Momberg from Fauna & Flora International (FFI) have now investigated the evolutionary history and relationships of the crested langurs. To this end, the researchers collected fecal samples from various species of the genus in the wild and in zoos, and they also used tissue samples from museum specimens. The DNA they obtained from these samples not only helped them reconstruct the family tree of the crested langur – it also revealed a new species.
Up to now it was assumed that the Phayre-eyeglass langur had two subspecies, Trachypithecus phayrei phayrei and Trachypithecus phayrei shanicus. The researchers’ analyzes showed, on the one hand, that these alleged subspecies are separate species that genetically separated about a million years ago. On the other hand, the researchers identified a new species that they named Trachypithecus popa, Popa langur. The name is derived from the mountain Popa, which is sacred in Myanmar. The largest population of the newly discovered monkey species lives here, with around 100 animals.
Genetic and morphological differences
“The genetic and morphological analyzes of museum specimens, which were collected more than 100 years ago for the London Museum of Natural History, ultimately led to the description of this new species, which was also confirmed by the fecal samples collected by the FFI research team in Myanmar” says Christian Roos. Compared to the closely related species of langur, which were previously grouped together as Phayre’s glasses langur, the Popa langur has larger teeth and a slightly longer skull. In addition, the Popa males have longer tails than Trachypithecus phayrei phayrei, and the fur on the head grows differently in all three species.
The Popa langur is widespread in the central dry region between two large rivers in Myanmar up to the foothills of a mountain range overgrown with rainforest. According to estimates by the researchers, the species comprises only 200 to 250 animals living in four isolated populations. “Just described, but unfortunately almost disappeared again,” says Frank Momberg. “Urgent action must be taken to save this species from extinction.”
Threatened with extinction
The Popa langur is endangered on the one hand because its habitat is getting smaller year by year. The rainforest is being cut down, new roads are being built and palm oil plantations are being created. On the other hand, the langurs are hunted in Myanmar – among other things because parts of them are considered medicinal products in traditional medicine. The researchers are now calling for the newly discovered species to be included in the Red List of Endangered Species and to be better protected in the future, for example by enforcing existing laws in Myanmar more and creating new protected areas.
“Describing species anew is important to describe the biodiversity on the planet,” says Roos in a video about the newly discovered species. “We have to know what is going on here and only then can we protect it. Given the current loss of biodiversity, on the one hand it is nice to describe a new species. On the other hand, when you see that the species is already endangered with a maximum of 250 animals, you have to take immediate measures to save this species from extinction. We are now trying to implement this with our cooperation partner Fauna & Flora International. “
Source: Christian Roos (Leibniz Institute for Primate Research, Göttingen) et al., Zoological Research, doi: 10.24272 / j.issn.2095-8137.2020.254