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,