Scientists Discover Six Tiny, New Species of Frogs in Mexico

A team of researchers has found six previously unidentified species of tiny, thumbnail-sized frogs in Mexico. One of the new species is Mexico’s smallest known frog.

Finding Mexico’s tiniest frogs

Experts from the University of Cambridge, London’s Natural History Museum, and the University of Texas at Arlington led the effort, which examined nearly 500 specimens. All the frogs within the study come from Mexico and belonged to the miniature Craugastor group.

“They’re small and brown and look really similar to other frogs,” explained Tom Jameson, the study’s lead zoology expert. “Frogs in the group known as Craugastor are very difficult to tell apart, so scientists have long suspected that more species may exist.”

Jameson’s team employed two distinct types of analysis on each specimen to identify variations among closely related animals: DNA sequencing and computerized tomography (CT) scanning. They created 3D models of the skeletons from the scans. Then they cataloged the specimens according to similarities in DNA and skeletal structure. That’s when they realized that they had found six previously unknown species.

Craugastor cueyatl. Photo: University of Cambridge

Craugastor cueyatl. Photo: University of Cambridge

 

And here’s a fun fact — all six types of frogs are ‘direct-developing,’ meaning that they skip the tadpole stage altogether, emerging from their eggs as fully formed little froglets.

The team found that one of the species, Craugastor candelariensis males is the smallest known frog ever found in Mexico, measuring a diminutive 13mm at maturity. By contrast, most species within the Craugastor group grow to 15mm.

Though candelariensis is relatively tiny, even smaller frogs exist outside Mexico. The smallest frog in the world is New Guinea’s Paedophryne amauensis, which is about the size of a housefly. Reaching a mere 7.7mm at maturity, the Paedophryne amauensis is also the world’s smallest known vertebrate.

Craugastor rubinus in a researcher's fingertips. Photo: University of Cambridge

Craugastor rubinus in a researcher’s fingertips. Photo: University of Cambridge

Conservation efforts on the horizon

Now that they completed the analytical work, the team is working to protect the tiny creatures. Due to the frogs’ miniature size, scientists believe they play a critical role in their ecosystems.

“With millions of these frogs living in the leaf litter, we think they’re likely to play a hugely important role in the ecosystem as a source of food for everything else, from lizards to predatory birds,” Jameson noted.

Some of the freshly identified species are what scientists call ‘micro-endemics.’ Micro-endemic species are isolated to one specific location — like a hilltop or marsh — and are unlikely to exist anywhere else. For that reason, micro-endemic populations are incredibly delicate; habitat disruption or disease can wipe out an entire species.

“We need to make sure that they don’t just get wiped off the map because no one even knows they’re there,” said Jameson.

But there is hope for future generations of these tiny frogs. Jameson’s team has found protected areas throughout Mexico where these new species live. They’re reaching out to nongovernmental organizations and local Mexican governments to engender a conservation plan.

Jilli grew up in the rural southern Colorado mountains, later moving to Texas for college. After seven years in corporate consulting, she was introduced to sport climbing. In 2020, Jilli left her corporate position to pursue an outdoor-oriented life. She now works as a contributor, an editor, and a gear tester for ExplorersWeb and various other outlets within the AllGear network. She is based out of Austin, Texas where she takes up residence with her climbing gear and one-eared blue heeler, George Michael.


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