A new species of frog with some bizarre mating rituals has been discovered in India, a new study says.
Found in swampy forests of the Western Ghats (map), the Kumbara night frog (Nyctibatrachus kumbara) mates while doing a handstand and then daubs its eggs with mud to protect them—the world’s only known frog species known to do so. (See: “Weird Purple Frog Seduces Females From Underground.”)
Hence the new frog’s name: Kumbara means “potter” in the language of the Uttara Kannada region of western India where the species lives, according to the research, published May 16 in the journal Zootaxa.
Watch a video of the male covering the eggs with mud.
When the male and female meet, they stand on their hind legs and touch the potential egg-laying site—usually a twig, plant, or rock that overhangs a stream, said study co-author Kotambylu Vasudeva Gururaja, an amphibian researcher at the Indian Institute of Science in Bangalore.
Then, during mating, the female performs a handstand with the male still on her back and starts laying her eggs, said Gururaja, whose team has observed and filmed the nocturnal frog, which was first glimpsed in 2006.
The male, having fertilized the spawn, leaps off, but the female remains in the handstand egg-laying position for up to 20 minutes.
Watch a video of the pair mating.
The study team suspects the pair start out standing on their hind legs in order to indicate where they want to lay the eggs, “but that needs to be checked out,” Gururaja said. (Also see: “Pictures: Mouth-Birthing Frog to Be Resurrected?“)
This ritual may also be a way for the female to check whether the male literally measures up.
“We hypothesized that the female might be checking the length of the male, since he will release sperms just a fraction of second prior to [egg laying],” he said. “If he is too small, sperms may not reach the eggs that are being attached against gravity.”
That may be why females don’t always go on to mate with smaller male suitors, Gururaja noted.
After the female lays up to seven eggs, the male takes over—revealing a previously unreported method of parental care by frogs. (Watch a video of a male Darwin’s frog spitting out its young.)
“They fill their two hands with mud, stand on their hind legs, then apply the mud,” Gururaja said. “They use their fingers in a similar way to us.”
This plastering job may take 25 minutes, and can involve 40 to 50 trips to the streambed and back, according to Gururaja.
The eggs themselves are secured tightly to the twig, he added, and are difficult for even a human to remove.
The study team suspects the frogs position their spawn above the stream and then conceal it to protect against aquatic predators like freshwater crabs, which “will eat anything, including frogs,” Gururaja said.
The mud casing may also play a role in helping to prevent the eggs from drying out. After a week or so, the tadpoles emerge and drop down into the stream.
The Kumbara night frog is just the latest in a string of recent frog discoveries from the Western Ghats, a range that extends up and down India for 990 miles (1,600 kilometers). (Related: “14 New ‘Dancing Frogs’ Discovered in India.”)
In 2011, Sathyabhama Das Biju, head of the Systematics Lab at the University of Delhi, described 12 new species of night frogs, including one that makes a meowing sound.
“Nyctibatrachus as a genus has amazing diversity in breeding behavior,” Biju, who wasn’t involved in the new study, said in an email.
He agreed the males’ mud-plastering is “unique,” adding that some frogs cover their eggs with mud to camouflage them and prevent them from drying out.
But the new frog’s egg-plastering technique, in combination with its other unusual breeding antics, “is an exciting find.”
“I believe more species will be described from this genus in the coming years,” Biju said.
What do you think about the frogs’ odd mating behavior?