Bizarre Tree Hole Breeding Frogs Rediscovered In India; Researchers Thought They Were Extinct

A bizarre species of tree hole breeding frogs thought to have gone extinct nearly a century ago was recently rediscovered in remote jungles of north-eastern India. After further study, biologist Sathyabhama Das Biju and a team of scientists from the University of Delhi have reclassified the frogs under an entirely new genus called Frankixalus.

These relatively small frogs – roughly the size of a golf ball when full-grown – live in tree holes up to 19 feet above the ground. Researchers believe this may be why the frogs have remained hidden for so long.

Their unusual tendency for living so far off the ground is not their only quirk. Tadpoles will feed on their mother's unfertilized eggs; and, unlike most other frogs, adults prefer to feast on vegetation rather than insects.

The new frogs were first discovered in 2007 by accident when researchers "heard a full musical orchestra coming from the treetops," Biju explained. "It was magical. Of course we had to investigate."

Since then, researchers have conducted an extensive study, including a DNA analysis, which confirmed the frogs were genetically unique.

Frankixalus also differs from other tree frog genera in terms of breeding, egg-laying, and development. For instance, the frogs breed in water that has accumulated in tree holes and they lay gel-encapsulated eggs that attach to the inside walls of the tree holes. Eggs that are not fertilized are saved for young tadpoles to feast on using smooth, suction-like mouths without teeth to pull in food. 

"This is an exciting find, but it doesn't mean the frogs are safe," Biju warned. Tropical forests are being cut down at an alarming rate that threatens unique species, such as Frankixalus. Industrial growth has also increased pollution, to which these frogs are particularly vulnerable. Researchers hope their discovery will lead to increased public awareness.

The findings were recently published in the journal PLOS ONE. 

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