Discovery of a 7 mm “Flea Toad,” Among the World’s Smallest Vertebrates

As their name suggests, “flea toads” are tiny amphibians. They belong to the genus Brachycephalus of the Brachycephalidae family, all species of which are endemic to Brazil. Flea toads measure a few millimeters long, or even a little over a centimeter.

Researchers have now identified a new species in the Brachycephalidae family. It was named Brachycephalus dacnis in honor of Project Dacnis, a conservation, research and education NGO.

This NGO maintains private areas of the Atlantic rainforest, including the area where the amphibian was discovered.

Miniature toads with all the characteristics of full-sized individuals

Specifically, the animal was observed near Ubatuba, a city that is on the coast of the state of São Paulo. A flea toad is literally a miniature toad.

As Luís Felipe Toledo, corresponding author of the study and professor at the IB-UNICAMP Institute of Biology, explains, they are “small toads with all the characteristics of large toads, except for their size. This genre is different. During its evolution it underwent what we biologists call miniaturization, which involves the loss, reduction and/or fusion of bones, as well as a reduced number of fingers and the absence of other parts of its anatomy.

B. dacnis thus becomes the seventh known species of flea toad of the Brachycephalus genus. The species already discovered were best known for their bright colors and venom. The new one stands out for its incredibly small size.

This flea toad is the second smallest vertebrate in the world

B. dacnis is actually the second smallest vertebrate in the world. It measures just under 7mm long. It strongly resembles another species, B. hermogenesi. Both flea toads actually have yellowish-brown skin and live in leaves on the ground.

It should also be noted that they do not have tadpoles. The young emerge from their eggs as miniature adults. They actually have the same morphology. So how did researchers differentiate B. hermogenesi from B. dacnis?

They noticed that the calls of the two toads were different. Sequencing the amphibian's DNA confirmed that it was indeed a new species unknown until now.

We must now remove any uncertainty between the two species of flea toads

However, “it may be that specimens belonging to the new species were found among those that served as the basis for the description of B. hermogenesi in 1998,” says Luís Felipe Toledo as reported by Physorg. He therefore suggests to use historical DNA sequencing tools to eliminate any ambiguity between the two species.

Historical DNA can be recovered from zoological museum specimens. This would make it possible to precisely determine the differences between the two amphibians. “The diversity of these miniature frogs may be much greater than we think. Hence the importance of describing as many traits and characteristics as possible,” adds the professor.

Source: Phys.org