A newfound species of rain frog in Ecuador is likely already endangered.

Scientists had long confused the amphibian with its close relative, Pristimantis ornatissimus, a well-known frog with a distinctive yellow-and-black body.

Juan Manuel Guayasamin, an evolutionary biologist at San Francisco University of Quito, and colleagues weren’t looking for a new species—instead, they were taking a closer look at the known one.

But the team noticed—first in photos and later in lab specimens—surprising variation in the markings between animals from the northern Chocó coastal region and the Andean foothills. (See "'Extinct' Toad Rediscovered in Ecuador.")

“We realized the northern frogs had longitudinal lines, while the southern ones had a more reticulated pattern,” says Guayasamin. Their eye colors also differed. “So we decided to look at the genetics.”

The genes revealed what the scientists' eyes had suggested: There were two distinct species among these colorful beauties. The new species, P. ecuadorensis, was announced recently in the journal PLOS ONE.

But scientists aren't celebrating just yet. The frog's rarity and tiny, threatened habitat means it meets the criteria to be listed as endangered by the International Union for Conservation of Nature, Guayasmin says.

A Special Kind of Frog

New species can evolve when geographic obstacles such as mountains or rivers separate animals for an extended period.

In this case, a group of frogs likely peeled off from the rest long ago as a result of physical separation—perhaps by a large river—and ultimately adapted to a new environment, becoming genetically distinct. (See "Shape-Shifting Frog Found, Goes From Spiky to Smooth in Minutes.")

That environment is upslope: The new rain frog, which is rare with a limited range in Ecuador's misty cloud forests, lives at least 1,150 feet higher than its relative.

This Frog Screams When It Gets Scared

These forests breed a special kind of frog. “Your typical textbook frog relies on a body of water to lay her eggs, but these forests are so steep, so there aren’t a lot of lakes and ponds,” says Guayasamin.

That’s led to an adaptation called direct development: “Females lay eggs on any wet spot—on a bromeliad or on leaf litter—and the embryos hatch as fully developed froglets”—skipping the tadpole stage entirely. (See "New Mating Position Adds to 'Frog Kama Sutra.'")

“So they’ve been able to colonize and thrive in areas otherwise empty of amphibian diversity.”

Vanishing Forests

But those areas are hardly pristine. “Most coastal forest in Ecuador has been logged and transformed into grasslands and agricultural lands,” Guayasamin says.

“It’s always exciting to find something new, especially something so beautiful,” he adds. “But anything we find here, especially on the coast, is already in trouble.”

View Images The newfound rain frog lives in a small area of Ecuador's misty cloud forests. Photograph by Jaime Culebras

P. ecuadorensis’s immediately dire status “is discouraging for sure,” Kelly Zamudio, an evolutionary biologist at Cornell University who was not involved in the study, says by email. (Read about vanishing amphibians in National Geographic magazine.)

That the species has a small range and is adapted to such specific local conditions “is a double whammy,” she notes.

“The bright side is that we know it is there now, and can do something about it."

Study leader Guayasamin hopes his study draws conservation attention to Ecuador's northern coast, which is rich with species yet has fewer protected areas than more tropical parts of the country.

“Everyone assumes Amazonian rain forest species are in the most trouble,” he says. “It’s time to highlight that the Chocó and western foothills should be a priority.”