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New Crocodile Species Discovered in West Africa

The views expressed are those of the author and are not necessarily those of Scientific American.


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slender-snouted crocodileStudying crocodiles in some of the world’s most remote and inaccessible places isn’t easy, but it’s all in a day’s work for researcher Matthew Shirley. It is also, as he says, a “crazy amount of fun”—even on the days when catching and studying crocodiles leaves him covered in his own blood. “I love cruising through these often very remote waterways at night with a hundred billion stars overhead and seeing these ecosystems through a new light—or really just my spotlight!”

Shirley, who recently completed his doctorate at the University of Florida’s Department of Wildlife Ecology and Conservation, has spent the past few years studying crocodiles in several African countries. His research has resulted in a major new discovery: a new species of crocodile that has been hiding in plain sight for thousands of years.

Catching crocodiles can be bloody work. © Matthew Shirley. Used with permission.

Until now the slender-snouted crocodile has been considered a single species, with a range stretching from Africa’s Atlantic coast in the Republic of the Gambia through central Africa and into the Democratic Republic of the Congo. But according to new genetic and morphological research by Shirley and others from the University of Florida, the slender-snouted crocodile is actually two species, one in central Africa and another, which is likely critically endangered, in west Africa. The discovery was published this past December in Proceedings of the Royal Society B.

Perhaps just as notable as the discovery of the new species, the paper confirms earlier research that indicates these slender-snouted crocodiles are not “true” crocodiles of the genus Crocodylus but rather belong to their own genus, Mecistops. The central African slender-snouted crocodiles are now known as M. cataphractus. The west African species is still awaiting a new taxonomic species name. Genetic tests indicate the two crocs have been separate for at least seven million years.

The paper—along with an early conservation assessment of all slender-snouted crocodiles that Shirley completed for the IUCN Crocodile Specialist Group in 2010 (pdf)—also indicates just how critically endangered the west African species has become due to decades of hunting and habitat degradation.  ”If our surveys are truly representative of this species status in the wild,” Shirley says, “west African Mecistops is easily one of the two or three most endangered crocodilians and, without question, one of the most endangered vertebrates in Africa.”

slender-snouted crocodile

Distribution of slender-snouted crocodiles, from the 2010 assessment

In fact, Shirley and his colleagues were not able to find many of the west African species. “Locating crocs in west Africa for sampling has always been a challenge,” he says. “The reality is that these species are heavily depleted in this region from a combination of hunting, conflict with largely artisanal fisheries, habitat degradation and alteration. To make matters worse, those crocs that are still present are alive largely due to their timidity making them highly unapproachable.”

The next step in this research—fully ascribing the new taxonomy for the two Mecistops species—also won’t be easy. The original sample from when the species was first described back in 1844 is long gone—”we believe it was destroyed during the London bombings in World War II,” Shirley says—so the researchers are almost starting fresh.

Meanwhile Shirley and his colleagues are preparing to publish another paper that genetically analyzes the slender-snouted crocodiles currently in zoos. “Our results show that for Mecistops only the west African species is present in the United States,” he says. “This is already a positive—not that this is the only species present but that we already have nearly 50 individuals of this species that can serve as a genetic repository.” He says he hopes zoos will establish a species survival plan for the new species and control breeding pairs to maintain genetic diversity. He also recommends institutions begin dedicated conservation efforts, which have proved incredibly effective for other crocodilian species that tend to breed well in captivity.

On top of that, the IUCN is currently reevaluating the slender-snouted crocodile, and the researchers hope the West African species will be formally assessed as critically endangered. The central African species would then likely maintain its current assessment of “vulnerable.”

The discovery of the West African slender-snouted crocodile brings the total number of known crocodile species in Africa to seven, up from three species just five years ago. The dwarf crocodile was divided into three species in 2009 and a 2011 study revealed that there are two species of Nile crocodile. Who knows what else is out there, hiding in plain sight?

Main photo: A central African slender-snouted crocodile photographed in Gabon. Courtesy of Matthew Shirley, University of Florida

John R. Platt About the Author: Twice a week, John Platt shines a light on endangered species from all over the globe, exploring not just why they are dying out but also what's being done to rescue them from oblivion. Follow on Twitter @johnrplatt.

The views expressed are those of the author and are not necessarily those of Scientific American.





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