Researchers say the flea toad measures just 6.95 millimeters in length and can fit on the tip of a finger.
The name of the new species, B. dacnis, pays tribute to Project Dacnis, a conservation, research and education NGO that maintains private areas of the Atlantic Rainforest, including the one where the animal was found, in Ubatuba, on the coast of São Paulo state.
Luís Felipe Toledo, corresponding author of the article and a professor in the Institute of Biology (IB-UNICAMP), said: "There are small toads with all the characteristics of large toads except for their size. This genus is different. During its evolution, it underwent what we biologists call miniaturization, which involves loss, reduction and/or fusion of bones, as well as fewer digits and absence of other parts of their anatomy."
The smallest vertebrate is a 6.45 mm individual belonging to a different species in the same genus (B. pulex) in the south of Bahia state.
An article on the study is published in the journal PeerJ Life & Environment