In what might be the cutest discovery in recent years, a team of researchers has identified seven new species of brightly colored miniature frogs in the southern Brazilian Atlantic rain forest.

How tiny are they? These amphibians — known as some of the smallest terrestrial vertebrates on Earth — could comfortably fit on a thumbnail, the adults often measuring less than a centimeter in length. Due to their diminutive size, even their physical structure differs from larger frogs. While most frogs have five toes and four fingers, these small relations from the genus known as Brachycephalus only have three toes and two fingers.

And because of their size, it was no easy task for researchers to find them. First, the frogs can only be found in cloud forests on a select few mountaintops, making them endemic to a very small area. Second, as humans, getting to this remote region in the rain forest is no piece of cake either, a contributing factor to the frogs’ anonymity. Besides, even if you're right next to 10 frogs, they're easy to miss.

"You can hear them singing, and there's probably hundreds of them, but you simply can't catch them!" said Marcio Pie, project leader and a professor at the Federal University of Parana. "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."

"Although getting to many of the field sites is exhausting, there was always the feeling of anticipation and curiosity about what new species could look like," said Pie.

Because the frogs are confined to such a localized area, most of the species in the genus were only discovered in the past 10 years. These particular frogs, found over the last five years, are the largest addition to the family.

The frogs can also be identified by their bright colors. In a press release about the findings, the researchers hypothesize that the members of the Brachycephalus genus display such dynamic colors as a warning to predators that their skin is laced with tetrodotoxin, a potent neurotoxin that can also be found in species like pufferfish, porcupinefish and ocean sunfish.

A new discovery, and then reason to worry

The scientists do have concerns over the survival of the frogs due to the narrow set of conditions they need to live. Because the frogs are limited to cloud forests atop mountains, they can't even migrate across valleys. Cloud forests are sensitive to climate changes, say the researchers. As some of these frogs only exist on one mountain, if the climate changed, the perfect conditions for their habitat might disappear.

According to Save the Frogs, amphibians are the most endangered group of animals on Earth with nearly a third of the species in danger of extinction due to human causes such as habitat destruction, pollution, pesticides, infectious diseases, climate change, invasive species and overharvesting.

Thankfully, due to the remote location, these frogs don't have to worry about humans trampling on their turf, but changes in climate could be a real threat in the coming years leading the researchers to speculate they might have to raise some in captivity to help manage the species.