The tropical forests of Ecuador are home to an astonishing diversity of frogs, with hundreds of known species – imagine what breeding season must sound like! And now, a new study has added yet another name to the list: Pristimantis ecuadorensis, the strikingly patterned Ecuadorian rain frog.

The researchers have described the new species as "spectacular-looking". Image: Jaime Culebras

Juan Guayasamin of the Universidad San Francisco de Quito and his colleagues weren't originally out looking for a new species. Instead, the team was exploring the Andes mountains in search of an already recognised amphibian: Pristimantis ornatissimus, the ornate rain frog. But during their work, the researchers discovered that the frogs were hiding a secret.

"We always thought that the impressive colour variation within the ornate rain frog could be at least partially explained by the existence of a different species," Guayasamin told me in an email. "The genetic work confirmed our suspicions."

Researchers have been collecting frogs from this region for decades, so Guayasamin, along with Chris Funk of Colorado State University, had a lot to work with. They were able to take genetic samples from museum specimens that hailed from the western slope of the Ecuador Andes and determine that one population didn't match the rest. Until now, no one had realised these unusual-looking frogs were a totally different species.   

Over 500 frog species are known to inhabit Ecuador, and nearly 200 of them are Pristimantis rainfrogs like this one. By now, the country has earned a fair share of frog fame – the region is so dense with these animals that discoveries are made fairly often. In a nod to all that biological diversity, the new find has been named the Ecuadorian rain frog. 

Less than a decade ago, Guayasamin and Funk tracked down another new frog species on the eastern slope of the Andes, named for its distinctive croaks. More recently, Guayasamin helped to discover an even more unusual amphibian called the mutable rain frog, which has the ability to change its skin texture to match its surroundings.

"Whenever field work takes place in remote areas, discovering new species is expected," Guayasamin said. The new Ecuadorian rain frog, however, was more of a surprise, since it popped up in an area where a lot of previous research had been done.

Pristimantis rainfrogs are stand-out amphibians. Not only are they extraordinarily diverse, but they also have an unusual life cycle. Unlike in most frogs, the eggs are laid on land, and the young skip right over the tadpole stage upon hatching: they emerge instead as tiny "froglets", all set up for life hopping around out of the water. This unique lifestyle may be what allows these animals to survive in such great numbers on tropical Andean slopes.  

The latest frog discovery may be exciting, but species typically don't go unnoticed for so long unless the population is small, and that can be a problem for long-term survival. As with many of its cousins in the region, the Ecuadorian rain frog's habitat is in decline, threatened by encroaching human activity.

Image: Jaime Culebras

"We have already evaluated the conservation of the species," Guayasamin said. "[I]t is clear that the species has suffered population declines and that the most likely driver of those declines is habitat destruction because of agricultural and cattle activities."

The new frog's name is meant to honour its home country, but the researchers hope it will also draw some much-needed attention and conservation action.

"There's so much diversity in the region – it's the reason we get into the field," Funk said in a press release. "We want to make sure this diversity persists into the future. This is what gets us up in the morning, and gets us excited about what we do."

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The research is presented in the journal PLoS One. It is the result of collaboration between the Universidad San Francisco de Quito (USFQ), Colorado State University (CSU), Tropical Herping (TH), and Reserva Mashpi.