Juan Guayasamin has spent years exploring the tropical climes of South America. The Universidad San Francisco de Quito professor has seen numerous amphibians as a result, since many different species live in these regions. One frog, however, stands out from the rest. It is, to use Guayasamin's word, "spectacular."
"It has a yellow dorsum [back] with black stripes," he told Seeker. "Its iris varies from light blue to grayish green."
The frog is a newly identified species that Guayasamin and colleague Chris Funk of Colorado State University have named Pristimantis ecuadorensis, the Ecuadorian rain frog. They describe it in the journal PLOS ONE.
"The discovery is surprising, mostly because of the colorful nature of this species," Guayasamin said. "Often times, the most beautiful species are readily recognized and described. The description of P. ecuadorensis is an exception to this rule."
The unique find occurred while he and Funk were performing genetic sampling of frogs from sites while crisscrossing the western slopes of the Ecuadorian Andes. Ecuador is ringed by a Pacific coastline, the Amazon basin in the east, and the Andes Mountains in the middle. DNA sequencing allowed the researchers to confirm that their spectacular frog, which hails from the Andes Las Pampas region, is indeed a new species.
The frog lives in a cloud forest, which is a moist tropical or subtropical forest characterized by persistent low-level clouds.
Usually distance or geographical barriers can lead to speciation. For example, a river or mountain range dividing two populations can limit gene flow, allowing species to evolve new traits over millions of years. Uniquely, the Ecuadorian rain frog appears to have become a distinct species in the absence of such geographical barriers.
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The researchers suspect that environmental differences led to the speciation. A close relative of the Ecuadorian rain frog, the ornate rain frog (Pristimantis ornatissimus), lives nearby, but in a lower elevation habitat.
"What we observed is that P. ecuadorensis is found at higher elevations than P. ornatissimus," Guayasamin said. "Thus, it is possible that the new species has adapted to colder microhabitats."
He added that mysteries still surround the Ecuadorian rain frog. He and his colleagues, however, have thus far determined that the frog is relatively small, with males measuring just under an inch long and females measuring about 1.5 inches long. The frog is nocturnal, perhaps helping to explain how it went undetected by humans until now.