Six new species of fingernail-sized frogs have been discovered in the forests of Mexico, and one of them earned the distinction of smallest frog in mexico.
The six species are smaller than a one peso coin Mexican, about 15 millimeters long, when fully grown.
Adult males of the smallest of these species, called Craugastor candelariensisgrow to only 13 millimeters.
“Until now these new species have gone unnoticed because they are small and brown and look a lot like other frogs,” said Tom Jameson, a researcher in the Department of Zoology and the Museum of Zoology at the University of Cambridgewho led the study.
“His lifestyle is absolutely fascinating,” Jameson added. “These frogs live in the dark, wet leaf litter of the forests, which is like a secret world: we really don’t know anything about what goes on there. We don’t understand their behavior, how they socialize or how they reproduce.”
The newly discovered species are known as “direct development” frogs: instead of hatching into tadpoles like most frogs, they emerge from eggs as perfect miniature frogs. And they are so small that they are right at the bottom of the forest food chain.
“With millions of these frogs living in the leaf litter, we think they likely play a very important role in the ecosystem as a food source for everything from lizards to predatory birds,” says Jameson.
The discovery, made by researchers at the University of Cambridge, the Natural History Museum, London and the University of Texas in Arlington, is published this month in the journal Herpetological Monographs.
The study involved collecting almost 500 frog specimens from museums around the world, which had been collected in Mexico, and using new methods to categorize the relationships between them.
Using DNA sequencing, the team classified the frogs into groups based on the similarity of their genes. Computed tomography was then used to create 3D models of the frogs’ skeletons so that the physical details could be compared. These two very different lines of evidence revealed six new species of frogs.
Jameson is particularly pleased with the name cueyatlwhich means ‘frog’ in the indigenous language, the Nahuatlwhich is spoken in the Valley of Mexico, where this species was found.
We chose the name cueyatl to honor the rich human history of the Valley of Mexico and the local people who have probably known these frogs long before us,” he said.
The team believes that the smallest of the six new species is Craugastor candelariensis, which grows to just 13 millimeters long. They found some specimens of Craugastor portilloensis that were smaller, but they couldn’t be sure they were fully grown adults.
But whichever of these species holds the new title of Mexico’s smallest frog hasn’t taken the world title. Adult males of Paedophryne amanuensis, a frog from Papua New Guinea, are even smaller, not even reaching 8 millimeters.
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