Deep in the remote tropical forests of the northern Andes, scientists have discovered three new species of extremely rare snake.

The discovery comes mere weeks after a separate team announced the discovery of a closely related snake in southwestern Ecuador. Taken together, the four newfound reptiles double the number of known fishing snakes of the genus Synophis—an elusive group native to South America known for their dark backs and light bellies.

Despite their name, scientists know next to nothing about how Synophis snakes feed and spend their time. (Also see "New Venomous Snake Found: Death Adder Hiding in Plain Sight.")

'Ugly' Salamander, New Frog Found in Ecuador The Andes mountain range, home to the Synophis fishing snakes, is one of the world's most diverse ecosystems. Check out this video about other animals recently discovered in Ecuador's forests.

“I have no idea where [the name “fishing snake”] comes from—they don’t fish at all,” says biologist Omar Torres-Carvajal of the Pontifical Catholic University of Ecuador, who led a study on the three most recently discovered reptiles in the journal ZooKeys.

Scraps of evidence suggest the skittish reptiles dine on small lizards and spend at least part of the time in underground burrows—perhaps explaining why they're so rarely seen.

View Images The newfound fishing snake Synophis zamora. It's unknown how the South American reptiles, which aren't known to fish for prey, got their name. Photograph by Omar Torres-Carvajal

Sorting Through Junk

Armed with cloth “snake bags,” hooks, and their bare hands, Torres-Carvajal and colleagues spent weeks combing Andean forests for unrecognized fishing snakes, eventually catching several.

DNA extracted from the specimens’ livers and muscles didn’t match any known fishing snake, suggesting they were entirely new species. But to be sure, the team closely examined a key detail in the male specimens: their genitals.

All male snakes have pairs of barbed sexual organs called hemipenes, which are normally tucked away inside the body cavity. (Related: "Beyond Testicles and Dads: 5 Legit Studies of Male 'Gear.'")

When the snake is about to mate, the hemipenes inflate with fluid and expand out of the body. Snakes only use one hemipenis at a time, keeping the other one tucked away as a spare if another mating opportunity arises soon after the first.

Because each species has its own unique type of hemipenis, scientists can use them to distinguish between snakes.

Sure enough, when the team examined the newfound specimens’ hemipenes, they were shaped and barbed differently both from each other and from any of the four known Synophis species. The team identified three new species: Synophis bogerti, Synophis zamora, and Synophis insulomontanus.

View Images All Synophis fishing snakes (pictured, the new species Synophis insulomontanus) have dark backs and light bellies. Photograph by Germán Chávez

Since Synophis snakes are rarely seen—and half of them were just discovered—it’s difficult to assess their conservation status.

But the Andean cloud forests the snakes call home are among the most diverse yet threatened ecosystems on Earth, as agriculture and oil exploration chip away at habitat.

Fishing for More

What's more, the newly found snakes may represent the tip of a scaly iceberg.

Recently, Torres-Carvajal helped discover eight new species of “dwarf dragons” in the same cloud forests of Peru and Ecuador, doubling the number of those species in one fell swoop.

The region is a hot spot for diversity—but one that still contains secrets, Torres-Carvajal says, especially considering that “43 of the 454 species of reptiles known to occur in Ecuador have been described in the twenty-first century.” (See National Geographic's snake pictures.)

“We need an army—a new generation—of taxonomists just to clarify how many species are around us.”