The new species belong to the genus Brachycephalus, a group of frogs known for their miniscule size and bright colors. These amphibians are among the smallest terrestrial vertebrates, with some species only growing to about about 0.3 inch (a centimeter) long.
Their conspicuous markings may warn potential predators that their skin contains highly potent toxins.
Most species of Brachycephalus are only found on one, or a few, mountaintops in Brazilian cloud forests. These species tend to be cut off from one another by valleys of unsuitable habitat that they are unable to cross, essentially forming isolated "sky islands."
Marcio Pie, a professor at the Universidade Federal do Paraná in Brazil, thought the inaccessibility of these mountainous habitats could mean they harbored previously undiscovered species. (See more pictures: "Pea-Size Frog Found—Among World's Smallest.")
So Pie and his team carried out a series of field expeditions to cloud forests in the southern Brazilian states of Parana and Santa Catarina to look for new frog species.
The new frogs care distinguished from one another based on their coloration and the texture of their skin. Pie says they are similar to other Brachycephalus species in terms of their overall body shape, tiny sizes, and poor jumping ability.
While the first Brachycephalus species was described in 1824, most of the species in this genus have been discovered in the past 15 years. This is partly due to the difficulty in reaching the remote sites in which they live.
"Field work usually involved from two to eight hours of steep trails to get to the sites, and the same time afterwards to get back," says Pie, whose findings were published June 4 in the journal PeerJ.
Now, Pie and colleagues have added seven species to the 21 Brachycephalus species already known. Pie expects that even more will be found in the next few years. (See "Smallest Frogs Found—Each Tinier Than an M&M.")
Although little is known about the populations of these new species, Pie and his team are concerned about their future.
Since the animals are restricted to cloud forests on one or a few adjacent mountaintops, they are vulnerable to extinction. Cloud forests are highly sensitive to climate changes and also face threats from deforestation for pine tree plantations and cattle ranching.
"Preserving these areas is crucial not only for conservation, but also to understand how such high levels of biodiversity were generated in the first place," he says.
Pie and his team are currently working with state and federal environmental protection agencies to propose the creation of reserves in this region of the Atlantic rain forest.