Newly discovered 'flea toad' is the world’s second smallest vertebrate

The flea toad, a tiny marvel smaller than a fingernail, resides deep within the heartlands of the Atlantic Rainforest.

Known for its diminutive size and unique characteristics, this intriguing amphibian has recently gained another member in its genus – a newly discovered species known as Brachycephalus dacnis.

The toad was named in honor of Project Dacnis, an NGO dedicated to conservation, research, and education.

Project Dacnis significantly contributes to the preservation of private regions within the Atlantic Rainforest, including the area where B. dacnis was spotted. This particular area lies within the charming coastal city of Ubatuba in the state of São Paulo.

Flea toad Brachycephalus dacnis

These small toads are nothing short of exceptional in the world of amphibians. They possess a unique set of traits that set them apart from their larger counterparts.

“There are small toads with all the characteristics of large toads except for their size. This genus is different,” noted study co-author, Luís Felipe Toledo, a professor at the Institute of Biology.

“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.”

Unearthing diversity amidst the leaves

Researchers have always found the genus Brachycephalus fascinating, particularly due to its colorful species and unique venom.

The recent focus, however, is on the puny stature of the flea toads belonging to the seventh species to be described in this genus.

The tiny toadlets of Brachycephalus share a unique quality. They are unable to hear their own vocalizations due to the absence of a tympanic middle ear.

This intriguing fact was uncovered in a 2017 article by Toledo and his team. The study, focused on pumpkin toadlets, indicated that visual communication has replaced acoustic communication.

Brachycephalus dacnis as a new species

Upon analyzing B. dacnis, the team found that it shares a lot of morphological similarities with another species – B. hermogenesi.

Both have a yellowish-brown skin, share the same habitat in leaf litter, lack a tadpole stage, and are found in the same region. However, the uniqueness lies in their calls — they are distinctly different.

DNA testing further confirmed their suspicion and identified B. dacnis as a new species that is found in the same region as B. hermogenesi.

Discussing the likelihood of the existence of B. dacnis among the specimen that aided in describing B. hermogenesi in 1998, Toledo suggested the use of historical DNA sequencing tools to clear up uncertainties.

These tools are crucial in gathering DNA from zoological museum and herbarium specimens.

Need for focused conservation efforts

The discovery of B. dacnis reveals the rich and possibly underestimated variety within the world of miniature frogs.

“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 said.

Advancing our understanding of these tiny amphibians is essential for their preservation and highlights the need for focused conservation efforts.

Ecological significance of flea toads

Flea toads, despite their tiny size, play a significant role within their ecosystem. Their presence in the Atlantic Rainforest highlights the importance of even the smallest creatures in maintaining ecological balance.

As insectivores, these diminutive amphibians help regulate insect populations, including species that may become pests if left unchecked.

By thriving within the leaf litter, they also contribute to the nutrient cycle, enriching the soil as they forage and interact with other organisms.

Understanding the ecological contributions of B. dacnis and similar species highlights why conservation efforts are vital – not only to protect the toads themselves but also to preserve the broader environmental health of this rich habitat.

The research received funding and support from FAPESP, a prominent research foundation, as part of the thematic project “From the natural history to the conservation of Brazilian amphibians.”

The study is published in the journal PeerJ.

Image Credit: Lucas Machado Botelho/Projeto Dacnis

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