#craugastor

Scientists have discovered six new species of frog the size of a thumbnail in the forests of Mexico, with one earning the distinction of Mexico's smallest frog.

All six species are smaller than a British 1p coin—around 15mm long—when fully grown. Adult males of the tiniest of these species, named Craugastor candelariensis, grow to only 13mm.

The newly discovered species are known as 'direct-developing' frogs: rather than hatching from eggs into tadpoles like most frogs, they emerge from the eggs as perfect miniature frogs. And they're so small that they're right at the bottom of the forest food chain.

The discovery, by researchers at the University of Cambridge, London's Natural History Museum, and the University of Texas at Arlington, is published in the journal Herpetological Monographs.

"Until now these new species have gone unnoticed because they're small and brown and look really similar to other frogs," said Tom Jameson, a researcher at the University of Cambridge's Department of Zoology and University Museum of Zoology, who led the study.

The study involved gathering 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.

The new species have been named Craugastor bitonium, Craugastor candelariensis, Craugastor cueyatl, Craugastor polaclavus, Craugastor portilloensis, and Craugastor rubinus. Jameson is particularly pleased with the name cueyatl—it means 'frog' in the indigenous language, Nahuatl, 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 far longer than we have," he said.

Known as 'micro-endemics', some of the newly discovered frogs may occur only in one small area, such as a hilltop in a certain part of Mexico. This makes them incredibly vulnerable.

"We named Craugastor rubinus after the garnet mines in the hillside where they're found," said Jameson. "Sadly, it will only take the expansion of one mine and these frogs could be gone.”

Six New Miniature Frog Species Discovered in Mexico

The amphibians are found under leaf litter and hatch fully grown

Hidden on forest floors in Mexico, scientists have discovered six new tiny frog species about the size of a thumbnail. At only a half inch long, one species (Craugastor candelariensis) is now considered Mexico's smallest frog.

The miniature amphibians have gone unnoticed by researchers because of their small stature, neutral brown coloring, and similarity to existing species, a statement explains. Details about the frogs were published last month in Herpetological Monographs.

The six amphibians were categorized in the Craugastor genus. They are known as direct-developing frogs, meaning they skip the tadpole stage and hatch as fully-formed adults, reports Liam James for the Independent. The frogs have not been witnessed hatching yet, but researchers suspect they are less than 10 millimeters, or 0.4 inches long, Live Science's Mindy Weisberger reports...