A rare Galápagos species, the “fantastic giant tortoise”, long thought extinct, has been officially identified for the first time in more than a century in what scientists called a “big deal” for the famed islands’ embattled biodiversity.
The animal is the first Chelonoidis phantasticus to be seen since a male specimen was discovered by the explorer Rollo Beck during an expedition in 1906. The newcomer has been named Fernanda, after the Fernandina Island, a largely unexplored active volcano in the western Galápagos Archipelago that she calls home.
“Everything that we knew about this species said it was extinct,” said Stephen Gaughran, an ecology and evolutionary biology researcher at Princeton University and one of the lead authors of the study that announced the finding, published on Thursday in the journal Communications Biology. “So it’s a big deal for a species that we thought was extinct for a hundred years to suddenly appear here.”
When Fernanda was discovered in 2019, roaming inside a vegetation clump among the solidified lava of the islet, it gave hopes to researchers that the rare phantasticus species wasn’t extinct after all, but it took DNA testing to confirm their hope.
Researchers at Princeton sequenced the genome of both the 1906 and the 2019 tortoise, matching them as members of the same species of fantastic giant tortoise, significantly genetically different from the other 13 species of tortoise found in the Galápagos.
All giant Galápagos tortoises are all listed on the IUCN Red List from vulnerable to critically endangered, with one species already extinct.
Fernanda is probably 50 or older but is smaller than the typical giant tortoise, probably due to the lack of vegetation on the arid, volcanic island. This was one of the reasons scholars initially doubted Fernanda was a native phantasticus species, as well as the lack of the species’ flared shell and saddleback shape.
Zoologists also initially thought that the 1906 specimen must have been transplanted to Fernandina Island. Although tortoises don’t swim, it’s not uncommon for them to float and be carried from island to island during extreme weather events or through human intervention, Gaughran said. “It seemed like a more likely explanation that a random tortoise just ended up there from a different island,” he said.
The discovery, however, suggests that however Fernanda got to the island, she might not have been alone, and that there could have been populations of the tortoise on the island at some point.
“These findings are extremely exciting from both evolutionary and conservation perspectives,” said Michael Russello, a biodiversity researcher at the University of British Columbia who was not involved in the study. “Fernandina is a challenging island to traverse, but this finding does suggest a comprehensive survey may be warranted to search for other individuals”, because there’s now “a glimmer of hope that the species may yet survive”.
There are deeper conservation implications to the discovery of Fernanda, according to Danielle Edwards, a Galápagos tortoise expert from University of California Merced, who was not involved in the study. There’s debate about whether these Galápagos tortoises are species or subspecies. “Biology is messy and speciation is a continuum,” said Edwards. So, finding another tortoise that is genetically similar to Fernanda, and making the most of these new analysis methods would be crucial to learn more about the mysterious history of these island inhabitants, she said.
Recent expeditions found the tracks of two or three other tortoises that could be from the same species, which, if confirmed, could spur local organizations to consider a captive breeding and repatriation program.
“If we only have Fernanda, it’s exciting to have found her. But if she doesn’t have another tortoise to breed with, then there’s nowhere to go,” said Gaughran. “If there are at least a few of these tortoises still living on that island, then that opens up the possibility of trying to really revive the species.”
