Written Off as a Figment, the Mysterious Clarión Nightsnake Reemerges after Nearly 80 Years

The snake was discovered on a remote Mexican island in the 1930s, but the notes of the famous naturalist who documented it were later called into question

The Clarion nightsnake, brought into the scientific light at last. Photo: Daniel Mulcahy

In 1936, the famous naturalist and explorer William Beebe set out from the San Diego coast on a yacht called Zaca. His destination was the Islas Revillagigedo, a remote Mexican archipelago about 700 miles west. Once there, Beebe set out doing what he did best: collecting biological specimens, which he later donated to the American Museum of Natural History.

One lone specimen in particular, a type of nocturnal snake referred to as a nightsnake, was declared a new subspecies, Hypsiglena ochrorhyncha unaocularus. But two decades later, when new teams of biologists arrived to Isla Clarión—the specific island Beebe said he found the specimen—they uncovered no trace of the snake. Beebe, the new researchers concluded, must have confused his records. The Clarión nightsnake was declared a figment, nothing more than the result of some faulty note taking.  

However, new evidence reveals that Beebe made no such mistake. After nearly eight decades, the Clarión nightsnake has emerged from hiding, researchers from the Smithsonian Institution and the Institute of Ecology in Mexico report in the journal PLoS One.

Zoologist Daniel Mulcahy, the lead author of the study, decided to pursue the long-standing mystery after discovering Beebe’s old specimen stashed at the museum. The Clarión snakes’ scale patterns, he realized, were indeed unique enough to likely represent a distinct subspecies. But the specimen’s DNA proved too old to provide any meaningful identity results, so Mulcahy decided get to the bottom of snake’s identity once and for all by traveling to Isla Clarión and having a look himself. 

Retracing Beebe's steps on Clarion Island. Photo: Daniel Mulcahy

While there, Mulcahy and his colleagues (accompanied by obligatory Mexican military personnel) relied of Beebe’s meticulous field notes to explore the island’s snake-friendly nooks and crannies. Donning headlamps after dark, the team spent hours digging through rocky piles or black lava and dense brush in search of the elusive reptile. Their efforts proved a success. All together, they uncovered 11 snakes that appeared to match Beebe’s description and original specimen. Five of those they kept as new scientific specimens, and the other six were sampled for DNA and released.

The snakes’ appearance—dark brown with distinct black dotted patterns—and isolated habitat hinted that they were probably distinct from other nightsnakes. Genetic analysis the team performed, however, clarified the extent of that uniqueness. Rather than a subspecies, the Clarión nightsnake is in fact a full species of its own, the team found. They renamed it Hypsiglena unaocularus in recognition of that correct distinction.

“Our study shows the importance of museum specimens, field notes and careful surveys to accurately document biodiversity,” the team concluded. They also noted that Beebe’s nightsnake was the only species ever known to simply be scratched off the scientific record due to what others assumed to be a collecting location mistake. As it turns out, however, Beebe was right all along.

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