Most people have difficulty tell alligators and crocodiles apart—it’s all about the snout. But telling one crocodile from another is a much more difficult, specialized task. That's why it took researchers almost 200 years to finally determine that a kind of crocodile found in central Africa is actually two species, reports Douglas Main at National Geographic.
The new species has been split from the West African slender-snouted crocodile, Mecistops cataphractus, and will be known as the Central African slender-snouted crocodile, Mecistops leptorhynchus with a range stretching from coastal Cameroon to the western edge of Tanzania. The split isn’t just academic. It whittles down the population of West African slender-snouted crocodiles to just 500 animals, making both species critically endangered. The official description of the new species appears in the journal Zootaxa.
“Recognizing the slender-snouted crocodile as actually comprised of two different species is cause for great conservation concern,” lead author Matt Shirley of Florida International University says in a press release. “We estimate only 10 percent of slender-snouted crocodiles occur in West Africa, effectively diminishing its population by 90 percent. This makes the West African slender-snouted crocodile one of the most critically endangered crocodile species in the world.”
Separating out the two species took substantial effort. The species was first described in 1824, but slender-snout crocs tend to live in very remote freshwater areas, are well camouflaged in high vegetation and are particularly skittish around people. Just getting DNA samples from animals in the wild was a difficult job “Basically this involved me running around 14 different African countries from 2006-2012, and I have not left the field since," Shirley tells Katherine Higett at Newsweek. “The fieldwork was long hours of paddling thousands of [miles] up and down rivers looking for crocs to sample, moving great distances between sites and countries dealing with local governments for research permission and export permits, not to mention new languages, cultures, and diseases like malaria.”
After all those years of effort and after contracting malaria 16 times, Shirley and his team were only able to collect samples from 15 to 20 animals. The research also meant tediously studying museum specimens, which was made difficult since the original “type” specimen kept at London’s Natural History Museum was probably obliterated by German bombs during World War II.
Despite all that, Shirley and his team were able to describe the two species. The newly split crocodile looks slightly different from its western counterpart, with smoother skin and smaller scales. It also lacks a bony crest on its skull that the other species has. DNA samples, however, sealed the deal, showing that the two species are genetically distinct. Main reports that genetics show the two crocs diverged about 8 million years ago, which makes sense. During that time period, volcanoes rose up in what is now modern day Cameroon, creating a geographic barrier between the two populations, cutting off any genetic exchange. After that, they each took their own evolutionary course.
Both species now face an uphill battle as poaching and habitat loss shrink their homes and population. That’s why Shirley and his team are working with NGOs and the governments of Côte d'Ivoire and Ghana to breed the crocs in captivity and release them in the wild. Currently over 30 slender-snouts are being raised at a Côte d'Ivoire zoo.
Shirley and colleagues are collaborating with the governments of Côte d'Ivoire and Ghana as well as a number of NGOs to breed the animals in captivity and eventually release them to the wild. The largest such effort is taking place at a zoo in Côte d'Ivoire where more than 30 of the animals currently reside.
“These are genuinely critically endangered,” Shirley tells National Geographic’s Main, “and [could] blink out at any moment.”
This isn’t the first revision to the crocodile tree of life in recent years. In 2009, researchers from the American Museum of Natural History used DNA analysis to split African dwarf crocodiles into three separate species. And in 2011, the Nile crocodile was also split into two species. Earlier this year, Shirley also investigated a cave in Gabon where strange orange-colored crocs were reported. Blood tests conducted on the dwarf crocs indicated that they were well on their way to diverging into a new species as well.