New mini-frogs discovered in Brazil - just 1 centimeter long

These newly discovered teeny-tiny frogs are about the size of your thumbnail

Researchers have discovered seven never-before-seen species of tiny frogs that are no bigger than your thumbnail.

The brightly colored frogs live high in the mountains of the Atlantic Forest in southeastern Brazil and they are all members of the genus Brachycephalus.

There are now 28 known species of Brachycephalus, and most of them don't grow more than a centimeter in length, making them among the smallest known land vertebrates.

They even have special adaptations to accommodate their tiny size. Most of the species have two toes on each front foot and three toes on each back foot, compared with four on front and five on back that most frogs have.

They are active in the day and were mostly found buried in the leaf litter. Many of them have brightly colored yellow and orange skin. Researchers think these bright colors may warn predators of the potent neurotoxin found in their skin.  

The first member of the genus was described by the German naturalist Johann Baptist von Spix in 1842, but more than half of the known species have been discovered in the past decade. That's because they live in remote mountain sites that are difficult for scientists to get to.

In a paper published in the journal Peer J, the research team explained that the frogs are highly endemic, which means they can only be found in very specific areas.  

"These species tend to be isolated from one another by valleys of unsuitable habitats, essentially forming 'sky islands,' " the authors write in the study. 

This isolation has likely led to the formation of new species, and the authors say there are definitely more out there.

"This is only the beginning, especially given the fact that we have already found additional species that we are in the process of formally describing," said Luiz Riberio, a research associate at Brazil's Mater Natura Institute of Environmental Studies, in a statement.  

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