“It underwent what we call miniaturisation”: bizarre new toad with missing body parts discovered in Brazilian rainforest

The newly described species of flea toad, found in the Atlantic Forest of São Paulo state, is the second smallest vertebrate in the world.

By Daniel Graham

Published: Tuesday, 05 November 2024 at 11:41 AM

Scientists have discovered a new species of flea toad on the coast of São Paulo state in Brazil.

The tiny amphibian is less than 7mm long, making it the second smallest vertebrate on Earth.

The toad has been named Brachycephalus dacnis (B. dacnis), after Project Dacnis, an NGO focused on conservation, research and education that safeguards stretches of Atlantic Rainforest.

The new species of flea toad was found in Ubatuba, on the coast of São Paulo state in Brazil/Getty

What is a flea toad?

Flea toads are tiny amphibians in the genus Brachycephalus that measure less than a centimetre in length – that’s smaller than a fingernail.

“There are small toads with all the characteristics of large toads except for their size,” explains Luís Felipe Toledo, corresponding author of the article (published in PeerJ) and a professor in the Institute of Biology. “This genus is different. During its evolution, it underwent what we biologists call miniaturisation, which involves loss, reduction and/or fusion of bones, as well as fewer digits and absence of other parts of their anatomy.”

B. dacnis is the seventh flea toad in Brachycephalus – a genus previously celebrated for its vibrant and toxic species, such as the pumpkin toadlet, known for its striking colours.

Meet the new species: Brachycephalus dacnis

The discovery of B. dacnis was guided by its distinct vocalisations, which set it apart from B. hermogenesi, a similar species that shares its yellowish-brown colour and habitat in the leaf litter of the Atlantic Rainforest.

Both of these species skip the tadpole stage and emerge from their eggs as tiny replicas of their adult form, but their calls – and, as DNA analysis confirmed, their genetic makeup – are different.

However, scientists believe B. dacnis may also be present in Picinguaba, where B. hermogenesi was first described in 1998, hinting that historical DNA analysis could reveal even more about this cryptic species.

Brachycephalus dacnis — B. dacnis male – note the missing digits/Bornschein et al.

To make B. dacnis distinct from its relatives, the researchers documented its skeletal structure, internal organs and unique vocalisations. Such thorough descriptions are crucial in distinguishing miniature species, which often appear nearly identical externally, says Toledo.

“The diversity of these miniature frogs may be far greater than we think. Hence the importance of describing as many traits and features as possible, to expedite the description process and get to work on conservation as quickly as possible,” Toledo concludes.

Main image: Atlantic Rainforest in Ubatuba, Brazil

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