Frog Discovered That Breeds in Tree Holes

The tree frog Frankixalus jerdonii emerging from a hole in a tree in northeastern India. SD BIJU

Tree holes: You probably don't think about them much. They're often difficult to see and easy to ignore. But to the frog species Frankixalus jerdonii, they are everything.

These little brown frogs lay their eggs on the cave-like walls of tree holes in northeastern Indian forests. They hatch and make their way into the shaded pools of rainwater in these arboreal cavities, and have the unusual habit of feeding on unhatched eggs of their own species. Then they grow up and try to find a choice tree hole to start the whole process over again.

A team of researchers from the University of Delhi and other institutes re-examined a group of frogs living in these tree holes, and found that one species living here had been taxonomically misclassified, and incompletely described in the late 19th century as 'Polypedates' jerdonii.

In a study published Wednesday in the journal PLOS ONE, the scientists conducted an in-depth analysis of several individuals, as well as a sequencing of the animals' genes that shows this species actually classifies as a new genus, the taxonomic grouping above species. The scientists renamed this creature Frankixalus jerdonii (after two of the study authors' mentor, amphibian specialist Franky Bossuyt of the Vrije Universiteit Brussel in Belgium).

The researchers found up to 19 eggs in the intestine of some of the tadpoles. The eggs appear to be unfertilized frog eggs of the same species, and likely come from the mother. The authors suggest that the mother lays these eggs to feed her own tadpoles. This would classify as a type of parental care, which is thought to only take place among a minority of amphibians.

The newly-classified tree frog Frankixalus jerdonii live in small holes in trees, and lay eggs on the side of tree holes which hatch and feed on unfertilized eggs. SD BIJU et al / PLOS ONE