A scientific foray up into the rugged cloud forests of the Bolivian Andes – a relative stone’s throw from the capital city La Paz – has uncovered an all-around treasure trove of biodiversity, including 20 previously undescribed species and a number of organisms that had been feared lost.

The Andean mountains of the Zongo Valley in Bolivia where the expedition took place are steep and rugged, with numerous waterfalls and cascades. Image © Trond Larsen

The area explored was Chawi Grande in the Zongo Valley, set within waterfall-flumed Andean highlands, partly fed by clouds blossomed out of the Amazon Basin, and an important source of drinking water and hydroelectricity for nearby La Paz. The two-week trek covered several thousand metres of elevation and documented better than 1,200 species, more than half of which were recorded in the watershed for the first time.

The 'lilliputian frog' (Noblella sp. nov.) measures approximately 10mm 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. Image © Trond Larsen

Among the newly described species is an amphibian running a mere 10mm from nose to rump: the aptly named Lilliputian frog, which has apparently eluded scientific gaze not only because of its vanishingly small proportions but on account of its “habit of living under tunnels beneath the thick layers of moss and humus” that cloak its cloud-forest haunts.

Also uncovered in this remarkably fruitful expedition was the mountain fer-de-lance – a pit viper – and the Bolivian flag snake, so-named because of its red, yellow, and green outfit.

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. Bothrops is a genus of pit vipers endemic to Central and South America. The generic name, Bothrops, is derived from the Greek words βόθρος, bothros, meaning "pit", and ώπς, ops, meaning "eye" or "face", together an allusion to the heat-sensitive loreal pit organs. Image © Trond Larsen
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. Image © Trond Larsen

Vertebrates weren’t the only lifeforms brand-new to science logged in the study: Four kinds of butterflies came on the radar, as did a number of plants – including a bamboo thus far not formally described but well known to native communities as qulqunch’awa, employed to make musical instruments.

This butterfly is one of two new species of metalmark butterflies (both in the genus Argyrogrammana) which were discovered on the Zongo RAP expedition in Bolivia. They feed on flower nectar in open areas and forest clearings. Image © Fernando Guerra
A species of bamboo (Merostachys sp. nov.), which although new to science, is well known by indigenous communities who use it to make musical instruments called sikus or zampoñas (they call the bamboo “qulqunch’awa”). Documented during the Zongo RAP survey in Bolivia. Merostachys is a Neotropical genus of bamboo in the grass family. It is found in South America and Central America from Belize to Paraguay. Image © Ivan Jimenez

Just as exciting as the new-to-science species, a number of organisms not documented for many years were “rediscovered.” Those called-back-from-the-brink creatures included the devil-eyed frog, with its dark skin and red peepers, until now known only from one specimen recorded more than two decades ago: The survey reckoned the species as “relatively abundant” in the Bolivian Andean cloud forest assessed. “Its elusive nature,” a Conservation International press release on the discoveries reads, “may be partly due to its habit of hiding beneath the thick moss and humus surrounding the roots of bamboo.”

Some 22 species tallied in the assessment land on the IUCN Red List as “threatened,” from the channel-billed toucan to the spectacled bear.

Conservation International announced the findings this week, stemming from fieldwork involving 17 researchers and co-led by the organisation’s Rapid Assessment Program (RAP) director Trond Larsen and the Municipal Government of La Paz’s Conservation and Wildlife Management head Claudia Cortez. The expedition came about through support from the National Museum of Natural History of Bolivia, the Bolivian National Herbarium, the Global Conservation Fund, the Andes Amazon Fund, and the La Paz government.

“As a haven for many newly discovered species and the source of water producing 11 percent of the electricity of the country, the importance of protecting the Zongo Valley is clearer than ever,” La Paz Mayor Luis Revilla said in a press release. “As La Paz continues to grow, we will take care to preserve the nearby natural resources that are so important to our wellbeing.”

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. Image © Steffen Reichle