A new mode of reproduction in a new frog

Forty different modes of reproduction have been described in frogs, now a 41^st mode has been described. The newly described kumbara night frog, Nyctibatrachus kumbara, inhabits stream and river beds traversing the forests of the southern India’s Western Ghats is the only known amphibian to coat its eggs in mud.

Kotambylu Vasudeva Gururaja of the Indian Institute of Science in Bangalore and colleagues, discovered the frog during expeditions which started in 2006. The new frog has only been found in swamp forests in the Karnataka region of the Western Ghats, where nutmeg trees form a dense canopy.

At dusk, male kumbara night frogs attract females with a distinctive "tok" call. If a female wishes to reproduce with him, the two stand on their hind legs, the female rotates into a handstand, and lays about five pigmented eggs on to a twig or some other plant structure.

The male then moves toward the egg clutch, stands on his hind limbs, collects mud from the stream bed with its forelimbs and spreads it on the eggs. He repeats this about 15 times, covering all the eggs with mud.

This is the first time such behavior has been observed in amphibians. "I have never heard of or observed mud packing in any amphibian," says Sathyabhama Das Biju at the University of Delhi in India, who was not involved with the study.

There are some straightforward explanations. "Since the eggs are laid about six centimeters above the water, there is a chance they can go dry," says Gururaja. "The mud pack could be preventing that. It could also be a camouflage against egg predators like crabs, insects and snakes."

But more fundamentally, Gururaja thinks the frogs just need to be different from their neighbors. Two closely related species of Nyctibatrachus, Jog's night frog and Rao's dwarf wrinkled frog, live in the same area. Gururaja found that the three species differ in many ways; they are different sizes, make different calls, mate differently and care for their young differently.

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