The Galápagos Islands are already famous for their unique reptiles, from giant tortoises to rock-dwelling marine iguanas. Now, scientists have announced the discovery of three new geckos to add to the list—and one of them lives on a volcano.

A team of U.S. and Ecuadorian herpetologists recently found one of the leaf-toed geckos during a grueling expedition to Wolf Volcano, the most remote of the five volcanoes on Isabela, the largest island of the Galápagos archipelago.

"It takes a long, very expensive expedition, and once you get there you have to climb the slopes of the volcano, which takes a lot of effort, and a big team,” says herpetologist Alejandro Arteaga, director of science for the Ecuador-based research and ecotourism group Tropical Herping. The organization led a three-year effort to document every Galápagos reptile for the production of a first-ever field guide to the reptiles of the Ecuadorian archipelago.

When the team first set out for Wolf Volcano, their goal was not to look for geckos, but rather to photograph the volcano’s pink land iguana, a species only formally described about a decade ago, says Arteaga. Still, the researchers had a hunch that other reptiles in the area might also be novel species, so they decided to track down some geckos as well. (Read how an “extinct” tortoise in the Galápagos was rediscovered after a century.)

Their hunch proved prescient. They named the new species Sabin's leaf-toed gecko, or Phyllodactylus andysabini, after American philantropist Andrew Sabin, whose nonprofit foundation provided financial support for the expedition. Like all geckos in the genus Phyllodactylus, the toes of these lizards are reminiscent of ginkgo leaves. In all, the three-year project, funded by multiple international nonprofits, documented 12 species of leaf-toed geckos in the Galápagos—eleven of which are found there and nowhere else.

Such research is crucial because roughly half of the islands’ 48 reptile species are either threatened or already endangered, and knowing more about them and where they live can help scientists and governments shape more effective conservation strategies. For instance, P. andysabini’s entire range is just 96 square miles, making it vulnerable to lava flows (the most recent eruption occurred in 2015).

"When you combine this with the fact that there are still introduced predators in the area, especially cats and black rats," says Arteaga, "it definitely qualifies as endangered."

In the name of science

Sabin’s leaf-toed gecko, together with the pink iguana and a species of giant tortoise also isolated to Wolf Volcano, Chelonoidis becki, now makes three types of reptile endemic to northern Isabela. "Why northern Isabela is so special is a question no one can answer [yet]," says Arteaga.

Meanwhile, the second new species from Isabela, called Simpson's leaf-toed gecko, Phyllodactylus simpsoni, was first identified as a species following a 2014 expedition led by Ecuadorian herpetologist Omar Torres-Carvajal. Since he never published a formal description of the gecko, Arteaga and colleagues picked up where he left off, naming the species after Nigel Simpson, one of the founders of the Ecuadorian conservation organization Fundación Jocotoco, an expedition sponsors.

View Images Once thought a subspecies of another gecko, Phyllodactylus maresi was described as unique. Photograph by Jose Vieira

The third new species, the Mares leaf-toed gecko, Phyllodactylus maresi, isn't technically new, since it was described in 1973 as a subspecies of Phyllodactylus galapagensis. It was then named for Italian businessman Lodovico Mares, who funded the expedition that discovered the animal on a tiny islet also called Mares—named after the same individual—near Santiago Island. But the team’s sophisticated genetic sequencing has revealed the gecko is indeed its own species. (Read about Lonesome George, the last of the Pinta Island tortoises.)

What is puzzling is that the researchers found the Mares leaf-toed gecko both on Santiago Island and Marchena Island, which are separated by some 40 miles of ocean. Nobody knows which island the animal inhabited first, but genetic data reveals the second colonization happened recently, fewer than half a million years ago—which is not enough time for speciation to occur.

Sharing geckos with the world

To Tony Gamble, who was not involved in the research, it's not surprising that these geckos went undetected for so long. That's for a very simple reason: tourists and researchers alike are generally only allowed within the islands' protected areas during the day, and geckos are nocturnal.

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"As soon as all the scientists and tourists leave, the sun goes down and the geckos come out. Based on their biology, [geckos] are particularly recalcitrant to study in the Galápagos," says Gamble, a herpetologist at Marquette University in Milwaukee. (Learn how geckos can turn their sticky feet on and off.)

Shining more light on these geckos and the plight of all Galápagos reptiles is actually why the scientists published Reptiles of the Galápagos both in print and as a free online download, rather than in a traditional scientific journal.