Just 16 km from Quito, the Ecuadorian capital, the rippled slopes of the Andes are home to one of the most biologically diverse and endangered places in the tropics.
At the foot of the Andes is a valley here. The river that runs through it, called Guayllabamba, is at the heart of a remarkable story of two newly identified species of glass frog.
One of them, Mashpi hyalinobatrachium, lives on the south side of the river in the Mashpi and Tayra Reserves, two private adjacent rainforest oases that together cover 6,200 acres. Other species of frogs Names in hyalinobatrachiuminhabits the northern flank of the valley of the Toisan Range, a rugged mountain complex isolated from the main belt of the Andes, an island floating above a green sea.
Both creatures exist at roughly the same altitude, under similar humidity and temperature conditions. They both measure between 1.9 and 2.1 centimeters from snout to vent (a standard amphibian length measurement). Their body is almost identical to the naked eye, with a lime green back dotted with black dots arranged around yellow spots.
Below, they both show the glass frog’s calling card: a completely transparent belly revealing a red heart, a textured white liver and digestive system, and, in females, a greenish egg sac. (Learn about a new species of glass frog discovered in Ecuador in 2019.)
“At first, when we started collecting them, we thought they were the same species,” explains Juan Manuel Guayasaminevolutionary biologist at San Francisco University in Quito and lead author of a paper describing the new species, published this week in the magazine PeerJ.
But when he and his colleagues took a closer look at the DNA of the frogs, “we were surprised to learn that they actually show great genetic differences.”
Sussing new frogs
There are 156 known species of glass frog living in the Neotropics, mostly in the northern Andes and Central America.
Over the past decade, Guayasamin, a National Geographic Explorerand his colleagues collected DNA samples from glass frogs, both by walking in the rainforest and by collecting specimens from museums and private collections in several countries.
So far, researchers have sequenced some genes for about 90% of the 150 extant species of glass frogs, he says. That’s how they found it H. mashpii and H. names genetically diverge by almost five percent, a large gap for otherwise similar amphibians.
Also surprising, says Guayasamin, is that the two groups live very close geographically, about 21 km apart. (Read about an “extinct” toad rediscovered in Ecuador.)
Because the Guayllabamba River valley is drier and ecologically unique compared to the adjacent slopes, “what we think is that the valley prevented these frogs from mixing with each other,” says Guayasamin. “When you have populations separated by a geographic barrier, you start to have an accumulation of mutations in each group, and over time they become genetically different.”
This is what scientists call cryptic diversity – in other words, the characteristics that differentiate a species are not visible to the naked eye, explains the study’s co-author Jaime Culebrasresearcher at Andean Condor Foundation, a Quito-based nonprofit that works to conserve frog-rich habitats. And cryptic diversity is very common among amphibians.
Besides genetics, the researchers used bioacoustics – reproducing and transmitting animal sounds – to determine the differences between frog species in the wild. However, they were only able to record calls from the male H. mashpii frog and compare the sound with those of other species of the Hyalinobatrachium kind.
“It looks like a cricket,” says Culebras, who is also a wildlife photographer. “But again, some crickets sound like this frog!”
A wealth of Andean diversity
The identification of the new glass frogs shows how many species remain to be discovered, particularly in the tropical Andes, says Andrea Teran, herpetologist at Jambatu Research Center in Quito, who did not participate in the study.
“The topography here is quite complex, with many unexplored niches and hard-to-reach areas, so endemism is very high,” says Teran. “In fact, when you’re talking about amphibians in Ecuador, the most diverse place is the Andes, not the Amazon.”
In fact, the tropical Andes – a region that includes parts of Venezuela, Colombia, Ecuador, Peru and Bolivia – are home to more than a thousand species of amphibians, twice as many as in the Amazon.
Some of the amphibians of Ecuador, such as the new H. mashpiieven live close to people, in the greater Quito metropolitan area, Culebras says.
“People don’t realize that the city extends well into the mountains, home to a staggering diversity of living things,” he says.
However, humans and their activities also pose a threat to these creatures: half of the amphibian species in the Andes are seriously threatened by copper and gold mininghe says. (Read about a controversial practice that could help Ecuadorian frogs.)
The International Union for Conservation of Nature lists 10 glass frog species as critically endangered, 28 as threatened, and 21 as vulnerable to extinction. It is too early to say if H. mashpii and H. names are among those endangered creatures, but Guayasamin suspects that they are.
“Once again,” he says, “nature is suffering from our myopic and unchecked extractivism.”