Biologists in India have spotted seven new species of night frogs, four of which are so tiny they could lounge comfortably on a human fingernail. The researchers published their findings in the journal PeerJ.

The frogs were discovered during a survey of local amphibians in the Western Ghats. Earlier explorations in the woods of Kerala and Tamil Nadu had uncovered numerous new members of the Nyctibatrachus (night frog) genus. Biologist Sonali Garg of the University of Delhi suspected the forests might still be hiding more.

She was right. Among the animals sampled were a number of frogs that just did not fit within known species. Most night frogs spend their time in streams, but these were found tucked into marshes and burrowed in leaf litter. On top of that, some of them were incredibly small—less than half an inch from head to rear, making them among the tiniest frogs in the world.

Robinmoore’s Night Frog (Nyctibatrachus robinmoorei) sitting on the Indian five-rupee coin (24 mm diameter).

 

 
Comparison of the frogs’ bodies, DNA, and chirps confirmed it: They’re too different from other night frogs to belong to existing species.

The frogs themselves have likely been right under scientists’ noses for a long time. “The miniature species are locally abundant and fairly common but they have probably been overlooked because of their extremely small size, secretive habits, and insect-like calls,” Garg said in a statement.

Unfortunately, staying hidden may not be enough to protect them. "Over 32 percent, that is one-third of the Western Ghats frogs, are already threatened with extinction,” study leader SD Biju said in the statement. “Out of the seven new species, five are facing considerable anthropogenic threats and require immediate conservation prioritization.”

All images courtesy of SD Biju