Two mysterious tree frogs found by a British naturalist in 1870 were long assumed to be part of a vanished species, never again found in the wild. Until now.

Scientists led by Indian biologist Sathyabhama Das Biju have rediscovered the frogs and identified them as part of a new genus — one step higher than a species on the taxonomic ranking.

The scientists say in a study published Wednesday by the Public Library of Science journal PLOS ONE that frogs from the new genus, Frankixalus, were found living in tree holes up to 6 meters (20 feet) off the ground in the rain-soaked jungles of northeast India.

The females demonstrate unusual behavior in laying fertilized eggs in water-filled tree holes and returning to feed the tadpoles with unfertilized eggs.