Imma Perfetto
Cosmos science journalist
Researchers have discovered a new species of flea toad in which one of the adults measured just 6.95mm in length – the second smallest adult vertebrate ever described.
Vertebrates are animals with a spine, which includes all fish, amphibians, reptiles, birds, and mammals.
But this new flea toad, Brachycephalus dacnis, which was found in the Atlantic Rainforest in Ubatuba on the coast of Brazil, is tiny. Only one related species of the genus is known to be smaller.
“There are small toads with all the characteristics of large toads except for their size. This genus [Brachycephalus] is different,” says Luís Felipe Toledo, herpetologist at The State University of Campinas Institute of Biology (IB-UNICAMP), Brazil, and corresponding author of the article describing the new species in PeerJ.
“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,”
The mini toadlets of the genus Brachycephalus come in 2 distinct forms: the brightly coloured, and highly toxic pumpkin toadlets and the smaller, more cryptic flea toads.
This is the seventh species of flea toad described. It is remarkably similar to the others, which also have yellowish-brown skin, live in leaf litter, and emerge from their eggs as fully formed miniatures of the adults. However, the males have distinctively different calls.
Interestingly, B. dacnis also retains the skeletal traits typically found in larger frogs which are lost or fused in other miniature frogs, such as pumpkin toadlets.
For example, the toadlets’ lack of tympanic middle ear means they can’t hear their own vocalisations. And they are too small for the fluid needed for balance to move around sufficiently in their head and have lost the ability to leap straight.
Due to their small size and tendency to blend in among the leaf litter, the researchers think the diversity of flea toad species is likely far greater than currently thought.
“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 says.
