Researchers working in India have discovered four new frog species so small they can comfortably sit on a human thumbnail, according to a new paper in the journal PeerJ.
The amphibians — known as night frogs — are some of the tiniest frogs ever found. They live on the forest floor and get their name from the insect-like calls they make while the moon is out. Researchers discovered them alongside three larger species in the Western Ghats, a mountain range in India that is home to hundreds of threatened plants and animals. This brings the total number of night frogs discovered in the area to seven.
Despite their abundance in the region, the team found the frogs only after spending years exploring the forests of Kerala and Tamil Nadu.
“[T]he miniature species are locally abundant and fairly common but they have probably been overlooked because of their extremely small size, secretive habitats and insect-like calls,” said lead author Sonali Garg, a researcher at the University of Delhi, in a statement.
Past studies have found 28 different species in the night frog group, Nyctibatrachus. Of those, three were smaller than 0.7 inches in length. Scientists uncovered the new ones by studying their physical features, call patterns, and DNA. This allowed them to determine that the frogs come from a group of amphibians dating back 80 million years.
However, while many new amphibians have been discovered over the past few years, many of them are critically endangered. For instance, the new night frogs live in areas beyond the protected habitats in the Western Ghats. This leaves them exposed to habitat disturbance, modification, and fragmentation. More than 32 percent of the Western Ghats frogs are already threatened with extinction, and five of the newly discovered species are going to need immediate action if they are to survive.
“This highly bio-diverse region contains many unique amphibian species and the area is under increasing threats from human disturbance,” said study co-author SD Biju, a professor at the University of Delhi, according to BBC News. “The discovery of these new species will increase our understanding of the conservation priorities for amphibians in the region.”