Researchers have found seven new species of the miniature frog genus Brachycephalus on seven different mountains in the Atlantic rainforest of Brazil.
Living separately from each other and forced by several factors to keep to their own mountain tops, the members of this genus have evolved into many varied - but hard to find - species. Most members of the genus are tiny - less than 15mm long.
The main difference among the frogs, many of which have fewer fingers and toes than most in order to optimise for their size, is skin colour and texture. They produce varying levels of a neurotoxin called tetrodoxin, and their bright skin colours are a warning to predators.
To find the frogs, researcher Marcio Pie of Brazil's Federal University of Parana and colleagues had to trek up small but rugged mountains, many of which lack well-marked trails. Since the area is so rich with members of the genus - and since the mountains clearly separate one species from another - it's pretty much assumed that each mountain searched for the first time will yield a new species. But the frogs are pretty hard to spot.
"It takes a lot of practice and sometimes it's very frustrating, to go up the mountain for many hours and come back empty-handed," Pie told the BBC. "You can hear them singing and there's probably hundreds of them, but you simply can't catch them. Because, once you get closer, just from the vibration in the ground, they keep silent for, say, 20 minutes or half an hour. And then you have to go through the leaf litter very carefully with your hands," he said.
