New Pumpkin Toadlet Species Smaller Than a Fingernail Discovered in Brazil’s Cloud Forests

A tiny amphibian highlights how much biodiversity still hides in Brazil’s mountains.

In the mountains of southern Brazil, a frog just over a centimeter long lives in the leaf litter of the forest floor.

It is bright orange, active during the day, and easy to overlook. Until recently, it had no name.

Now scientists have formally described it as a new species: Brachycephalus lulai, a pumpkin toadlet found only in a small stretch of cloud forest in the Serra do Quiriri, in Santa Catarina. The description was published in December in the journal PLOS One .

The newly discovered species adds to a growing list of miniature frogs known only from isolated Brazilian mountaintops.

Found by Sound

Many pumpkin toadlets are orange. But what caught the researchers’ attention was its call.

Male frogs produce mating calls that are specific to each species. While surveying the Serra do Quiriri, scientists heard a pattern they had not recorded before: pairs of short notes, repeated in bursts.

By following the sound, they located calling males hidden beneath leaves. Females, which do not call, were collected less systematically.

Back in the lab, the team compared the frogs with closely related species. They analyzed DNA, scanned skeletons using CT imaging, and measured body proportions.

Males measured 8.9 to 11.3 millimeters long, while the larger females reached up to 13.4 millimeters. The frogs also differed in skin texture, coloration, and call structure.

Together, the evidence showed this was a distinct species.

An Isolated Tiny Frog

Brachycephalus lulai lives more than 750 meters above sea level, in cool, wet cloud forest. Two close relatives occupy nearby mountaintops, separated by valleys that the frogs cannot cross.

Over long periods, climate shifts likely pushed forests up and down mountain slopes. As forests contracted, frog populations became isolated on peaks, allowing for new species to form.

This process helps explain why pumpkin toadlets have such small ranges. Of the 42 recognized species in the genus Brachycephalus, 35 have been described since 2000. Many are known from just one or two locations.

The researchers named the new frog after Brazil’s president, Luiz Inácio Lula da Silva. “Through this tribute, we seek to encourage the expansion of conservation initiatives focused on the Atlantic Forest as a whole, and on Brazil’s highly endemic miniaturized frogs in particular,” the authors wrote.

Creating a Refuge

For now, the outlook for B. lulai is relatively stable. Its habitat remains largely intact, and the researchers classify it as being of least conservation concern.

That does not mean it is safe.

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Amphibians are the most threatened group of vertebrates globally. In Santa Catarina, several related frog species are already critically endangered.

The threats are familiar: grassland burning, cattle grazing, invasive plants, tourism, mining, and deforestation. Any could encroach on the Serra do Quiriri.

To reduce that risk, the researchers propose creating a federal wildlife refuge that would protect forests without requiring the government to buy private land.

The frog’s discovery is a reminder of how much biodiversity remains undocumented. Sometimes it takes years of listening and careful measurement to realize an unknown species was there all along.