New monkey species found hiding in plain sight

Three Southeast Asian leaf monkeys are distinct species, new research shows, which makes two of them some of the rarest, most endangered primates.


The newly described East Sumatran banded langur (Presbytis percura) qualifies as critically endangered—it’s now one of the rarest and most imperiled primates.

For more than a century, scientists considered banded langurs, a type of reclusive, tree-dwelling monkey, to be a single species—but new research points to three separate ones. They've been hiding in plain sight, due to differences that couldn't be readily observed.

Found throughout Myanmar, Thailand, Malaysia, Singapore, and Indonesia, the monkeys were not considered at risk of imminent extinction, in part because of this broad range. But the new findings, published in June in Scientific Reports, reveal that two of the new species are among the most endangered primates in the world, in urgent need of protection.

The research highlights the ability of cutting-edge genetic sequencing tools to correct centuries-old taxonomic errors that could be concealing conservation emergencies. In this case, the researchers worked with DNA found in monkey droppings, a non-invasive technique that could be more widely used in this field of science.

“We want this paper to encourage more research on these totally different species of monkeys in Asia,” says Andie Ang, a National Geographic explorer and research scientist at the Wildlife Reserves Singapore Conservation Fund. “There’s definitely...

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