Scientists working in Africa have uncovered a new crocodile species hiding in plain site, according to a paper published in the Proceedings of the Royal Society B. Looking at the molecular data of the slender-snouted crocodile, the researchers discovered two distinct species: one in West Africa and another in Central Africa. Although mostly lumped together as one species (Mecistops cataphractus) for over a hundred and fifty years, the scientists found that the two species have actually been split for at least seven million years, well before the evolution of hominins.
Lead author Matthew Shirley says the discovery of the new crocodile was “simply a matter of going to places people before us never wanted to go or thought possible to go.”
“West and Central Africa have been rife with civil unrest, disease and a lack of infrastructure the past 50–100 years,” the postdoc researcher with the University of Florida adds. “Many of the sites we visited to sample and survey required expedition efforts that Stanley and Livingstone themselves would have been envious of. But in the end all it really took was collecting the samples and analyzing them in a rigorous way—it was a discovery waiting to happen!”
Shirley and his team not only differentiated the two species via genetics, but also by outlining telltale morphological (physical) differences. Such differences were actually recognized in the past, according to Shirley.
The Central African species of slender-snouted crocodile in Gabon. Photo by: Matt Shirley, UF/IFAS.
“There were actually two different species of slender-snouted crocodile, as well as one subspecies, described historically. Over the years these were all synonymized with Mecistops cataphractus, but we are now faced with the necessity of determining if any of these previous names is equally applicable to the new taxa.”
This leaves the new croc without a new name, at least for the time being, as Shirley and his team attempt to discover if any past name may take precedence. But more importantly, the new species changes the conservation outlook for the Africa’s slender-snouted crocodiles, which make-up their own genus. Shirley says the split between the two species means the West African slender-nosed crocodile is on the verge of extinction.
“Over the past eight years of effort I and others have detected less than 50 slender-snouted crocodiles in the wild in West Africa, and of these less than 7 were adults, compared to nearly 2,000 in Central Africa over the same time period and survey effort. We recently evaluated its status for the 2014 IUCN Red List and found that it is Critically Endangered making it one of the top crocodilian conservation priorities globally rivaling the decline of gharials, Siamese and Orinoco crocodiles.”
Shirley says the recognition of a new, Critically Endangered crocodile means that it’s time for drastic conservation action, including possibly reintroduction from captive populations.
African crocodile taxonomy has been overturned in recent years. Not long ago, scientists recognized only three crocodiles in Africa: the slender-snouted, the Nile crocodile (Crocodylus niloticus), and the dwarf crocodile (Osteolaemus tetraspis). However, in recent studies (also involving Shirley) researchers have argued that there are actually two distinct Nile crocodile species and three distinct dwarf crocodiles. If the scientific community recognizes all these new species, Africa’s crocodile diversity will go from three species to seven, changing not only our understanding of crocodile evolution but also of conservation needs.
Citations:
- M. H. Shirley, K. A. Vliet, A. N. Carr, J. D. Austin. Rigorous approaches to species delimitation have significant implications for African crocodilian systematics and conservation. Proceedings of the Royal Society B: Biological Sciences, 2013; 281 (1776): 20132483 DOI: 10.1098/rspb.2013.2483
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