Frogs that build underground ‘sex nests’ to mate with their partner have been found by a team of researchers.

The intriguing males build these secret chambers to avoid predators.

The discovery was made by researchers in the Atlantic forest of Serra do Japi in the State of São Paulo, Brazil.

A new species of frog has been found in Brazil. Called Hylodes japi, it was found to mate underground in secret chambers. Males and females typically find a spot to mate in about five minutes. And the male will cover up the eggs to protect them from predators. Shown is another torrent frog, the Waterfall frog

The new species of torrent frog, reported by New Scientist, is called Hylodes japi.

The amphibian, part of the Hylodes lateristrigatus group, is characterised by light stripes on its size, while it is also relatively small, according to the researchers.

And when it comes to mating, this family of frogs has a unique trait not seen in other frogs.

They typically like to live near fast streams and, if a pair decides to mate, they will spend five minutes searching for a private spot.

‘The male quickly carves out a chamber by excavating the sand around small rocks at the bottom of the stream,’ said Agata Blaszczak-Boxe from New Scientist.

‘Then, like Christian Grey from Fifty Shades he invites his mate into his sex dungeon, which is only just big enough to fit the two amorous amphibians.’

The amphibian, part of the Hylodes lateristrigatus group, is characterised by light stripes on its size, while it is also relatively small, according to the researchers. It was found in the Atlantic forest of Serra do Japi in the State of São Paulo, Brazil

Once the female has laid her eggs, the male then covers up the entrance with sand from the stream.

The reason for this is not only to protect the eggs from predators, but also from tadpoles of the species - as they are known to be cannibalistic.

Finding the frogs wasn’t easy, either - they are so secretive that the researchers had to don camouflage gear in order to observe them.