They could hear the frogs everywhere. But they couldn’t see them.

Amid heavy rains in March 2017, 17 scientists trudged deep into the cloud forests in Bolivia’s Zongo Valley to scour the mountains for life. They brought everything they needed for two weeks. They set up two camps. Then, the researchers started documenting what lived in this misty, largely untrammeled forest in the Andes. On Monday, Conservation International, a conservation organization, released the detailed results of the expedition.  

“You cross a rope bridge and backpack into the mountains,” said Trond Larsen, the director of Conservation International’s Rapid Assessment Program (RAP) who co-led the expedition. “It’s rugged and steep. It’s not easy work by any means.”

Larsen and company spotted 20 species that are new to science and overall recorded 1,204 plants and animals. In such remote, high-elevation places with unique microclimates, biologists expect to find unique species, especially insects, as millions of insect species are believed to remain undiscovered. Yet in addition to the likes of four new butterfly species, the expedition also found three vertebrates previously undescribed by scientists: two snakes and a frog.

The lilliputian frog was especially difficult to find. Not only does it often burrow in tunnels under thick carpets of moss, it’s also just some 10 millimeters long. “It’s so tiny,” said Larsen.

These expeditions into little-known, inaccessible places are a boon to biodiversity researchers and our greater understanding of what’s out there.

“Conservation International’s RAP’s are eagerly awaited by biodiversity scientists and naturalists the world over,” said Seabird McKeon, an evolutionary ecologist and fellow at the University of Central Florida who had no involvement with the expedition. “It is appropriate that the news of this treasure chest of biodiversity comes during the holiday season. What makes this study remarkable is that many of the species are likely to be endemic, or found only in this one very particular region.”   

The cloud forests — wet mountainous regions that are often immersed in clouds — up in the high Andes are places where endemic species thrive. Animals here are largely cut off from the world. High, sharp ridges can separate one valley from another. “Over great amounts of time each valley becomes a ‘lost world’ filled with species found nowhere else,” marveled McKeon. 

The tiny frogs are a superb example. Up in the misty mountains, they hatch from eggs into fully developed froglets (they don’t develop in water and potentially travel down streams as tadpoles like most frogs). They are members of a special, niche community.

“They are like Tolkien’s hobbits. They stay hidden and safe.”

“Cloud forest species are not travelers,” explained McKeon. “They are like Tolkien’s hobbits. They stay hidden and safe.”

What follows are images of new-to-science species found on the expedition, rediscovered species (once thought extinct), or simply unique species found in the high Andes.

The 'mountain fer-de-lance' pit viper.

The ‘mountain fer-de-lance’ pit viper.

Image: Trond Larsen

From Conservation International: “Pit Viper in striking mode. The ‘mountain fer-de-lance’ is a new species of pit viper that was discovered on the Zongo RAP survey. It has since been described as Bothrops monsignifer.”

The 'Bolivian flag' snake (Eutrachelophis sp. nov.)

The ‘Bolivian flag’ snake (Eutrachelophis sp. nov.)

Image: Trond Larsen

From Conservation International: “The ‘Bolivian flag’ snake (Eutrachelophis sp. nov.), a slender terrestrial snake distinguished by red, yellow, and green colors similar to the Bolivian flag. This new species of diurnal snake was found in the thick undergrowth of stunted elfin forest along the crest of the mountain at the highest elevation surveyed during the Zongo RAP in Bolivia.”

The 'lilliputian frog' (Noblella sp. nov.)

The ‘lilliputian frog’ (Noblella sp. nov.)

Image: Trond Larsen

From Conservation International: “The ‘lilliputian frog’ (Noblella sp. nov.) measures approximately 10 mm in length (about half the width of a dime), which may make it the smallest amphibian in the Andes, and among the smallest in the world.” [New species]

The “devil-eyed” frog (Oreobates zongoensis).

The “devil-eyed” frog (Oreobates zongoensis).

Image: Trond Larsen

From Conservation International: “The “devil-eyed” frog (Oreobates zongoensis), which was previously known only from a single individual observed more than 20 years ago in the Zongo Valley, was rediscovered on the Zongo RAP expedition in Bolivia. It was found to be relatively abundant in the cloud forest where it had not been seen for more than 20 years. Previous expeditions attempting to find this black frog with red eyes concluded empty-handed. Its elusive nature may be partly due to its habit of hiding beneath the thick moss and humus surrounding the roots of bamboo.”

Chironius scurrulus, sometimes known as the smooth machete savane.

Chironius scurrulus, sometimes known as the smooth machete savane.

Image: Trond Larsen

From Conservation International: “Chironius scurrulus, sometimes known as the smooth machete savane, climbs shrubs and trees in search of frogs and lizards to eat. Found on the Zongo RAP expedition in Bolivia.”

A 'pleasing fungus beetle' (Erotylus voeti).

A ‘pleasing fungus beetle’ (Erotylus voeti).

Image: Trond Larsen

From Conservational International: “A ‘pleasing fungus beetle’ (Erotylus voeti) observed on the Zongo RAP expedition in Bolivia. These beetles feed on fungus and represent just some of the incredibly diverse beetle assemblages in the Zongo Valley.”

A preying mantis seen in the Zongo expedition.

A preying mantis seen in the Zongo expedition.

Image: Trond Larsen

From Conservation International: “A preying mantis observed on the Zongo RAP expedition in Bolivia. This species is an excellent mimic of dead leaves and hangs camouflaged from branches where it sways gently back and forth as if it were a dried leaf blowing in the breeze while it waits for insects to prey upon with its raptorial front legs.”

A new species of metalmark butterfly (Setabis sp. nov.)

A new species of metalmark butterfly (Setabis sp. nov.)

Image: Trond larsen

From Conservation International: “A new species of metalmark butterfly (Setabis sp. nov.) discovered on the Zongo RAP expedition in Bolivia. This species flies in the cloud forest canopy where it feeds on flower nectar.” 

Mercedes' robber frog (Yunganastes mercedesae).

Mercedes’ robber frog (Yunganastes mercedesae).

Image: Trond Larsen

From Conservation International: “Mercedes’ robber frog (Yunganastes mercedesae) is an extremely rare cloud forest frog that was previously only known from four sites in Bolivia and one in Peru until it was observed on the Zongo RAP expedition in Bolivia.”

The wilderness captured on the Zongo expedition.

The wilderness captured on the Zongo expedition.

Image: Trond Larsen

From Conservation International: “Cloud forest and elfin forest characterized much of the area surveyed on the Zongo RAP expedition. Thick layers of moss, with abundant orchids, ferns and bromeliads were interspersed among bamboo and trees adapted to the montane climate.” 


The message from the expedition is clear. Zongo is a stronghold for species that are either found nowhere else on Earth or almost nowhere on Earth. “But only if we protect it,” stressed Conservation International’s Larson. “Whatever we can do to ensure conditions for endemic species to exist is essential.”

The current rate of global extinctions is now estimated to be tens to hundreds of times higher than the average over the last 10 million years, according to the UN. This is largely due to loss of habitat, exploitation, and accelerating climate change.

Proving, or confirming, that a place is teeming with diverse species is a major reason why Larson and Conservational International undertake these expeditions. Diversity reports show why preserving a new place is warranted. These new findings, other than inherently providing wonderment, are meant to “inform sustainable development plans for the rural areas of La Paz [the third-most populous city in Bolivia], 78 percent of which falls within the Zongo,” the organization said.

“This is the tip of the iceberg.”

There’s a lot out there waiting to be discovered. Especially in the Andean mountain range, which is some 4,300 miles long. Each valley is likely home to unique species, said McKeon. 

“There’s so much that we still don’t know, it’s incredible,” said Larson. Biologists, however, can estimate what’s still out there based on the rate of discoveries in places like the Zongo Valley. “Those estimations indicate that it’s a lot,” he said. (There are likely millions of species that haven’t been documented by science.)

So when a fascinating frog is discovered in the high mountains, it also leaves researchers wondering what species of snail or insects those frogs might eat, and if those species are unique, too. 

“This is the tip of the iceberg,” said McKeon.

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