Even though some taxonomists believe that we have only described less than 10 % of all the species in the world, it's not an everyday occurrence that we get a new species of a large animal. When this happens, it tends to be because the animal has been hiding in plain sight, and this is pretty much the story of how we got a new species of crocodile, the first new crocodile species described since 1935!
The crocodile in question is found in Africa, and has been hiding as part of another species until now. It has been proposed the name Central African slender-snouted crocodile (Mecistops leptorhynchus), and until now no one knew that this species was different from the West African slender-snouted crocodile (Mecistops cataphractus), which used to just be called "African slender-snouted" until it got separated into two species.
A West African slender-snouted crocodile. It surely lives up to the name "slender-snote" in my opinion. Photo by Faux Gavial, posted with the Creative Commons Attribution 2.0 Generic license.
Both species of crocodiles are considered "medium length", but that still allows grown males to reach over 4 meters in length. They feed primarily on fish, which is why they have evolved to have a very long snout. This snout makes them easily distinguishable from other crocodile species.
You can find these crocodiles in tropical rainforests along the shores of very shallow rivers. They prefer freshwater, but they have also been found in brackish estuaries. They are notoriously difficult to find in the wild, not only because they are few in number, but also because they tend to be both shy and have good camouflage both in the river and on land. They are apparently very difficult to study, so we don't know a whole lot about the wild behavior of either of the two species right now, but we've learned a lot of them by keeping them on zoos and private collections.
Despite being in zoos and on farms (where they are bred for crocodile leather), no one had really paid much attention to the different varieties of the African slender-snouted crocodiles until now, when a research group from Florida International University spent several years looking at it.
How researchers found the crocodiles to be two separate species
The research group who identified them to be two separate species began their work several years back, and published the first paper with proposal to change the species into two species back in 2013 with the paper "Rigorous approaches to species delimitation have significant implications for African crocodilian systematics and conservation". This paper was the groundwork for the newly published "Systematic revision of the living African Slender-snouted Crocodiles (Mecistops Gray, 1844)" that actually solidified the claims that it should be divided into two species.
Photo is Public Domain.
The original 2013 paper used genetic testing on over 100 individuals to see how different they were, and categorized them into groups based on how much genetic material they shared. While this paper provides a good indication that this crocodile might not only be a single species, it took them another 5 years to publish a taxonomic revision proposal, which was just accepted by the journal Zootaxa a week ago.
Taxonomy can be a difficult research field to navigate at times, but this newly published paper should likely set an end to the debate and uncertainty of the status of the crocodiles. The differences combined with fossil-calibrated phylogenetic reconstructions estimated that these two actually separated from each other between 6.5 and 7.5 million years ago, so it's not like they are "new species" by evolutionary standards. Their genetic difference is over 5 %, which is just a little bit more than the difference between humans and chimpanzee.
There is also a small morphological difference, and the Central African slender-snouted crocodile has a softer, smoother appearance compared to the Western species. The latter one also has heavier scales, rougher skin, and lack a bony crest on the skull that is found on the Central African slender-snouted crocodile.
A Central African slender-snouted crocodile. Photo by Wikimedia Commons user Leyo, posted with the Creative Commons Attribution-Share Alike 2.5 Switzerland license.
The consequences of having two species instead of one
I know that some of you might be wondering "why should I care?" right now, and I can understand that. It's not like everyone loves reading about taxonomy, but let me tell you, there is a big real-life consequence of it being divided into two species!
With information that makes these crocodiles two species, we now have to create new conservation strategies that ensures that both species will survive. The old African slender-snouted crocodile was already considered Critically Endangered by the IUCN Red List, with estimations of only having 1,000 to 20,000 individuals left in the wild. This is of course a big problem, but the West African slender-snouted crocodile could have as few as 500 individuals left! This put it right on the brink of extinction, and this new change should hopefully spark some serious efforts into preserving it as soon as possible. If not, we might soon go back to only having one species of African slender-snouted crocodiles..
The current range of where the two crocodile species are found. It's a huge area for very few animals, which makes them difficult to find. Map is generated by IUCN.
Sources
- Shirley, M.H. et al. 2018. Systematic revision of the living African Slender-snouted Crocodiles (Mecistops Gray, 1844), DOI: http://dx.doi.org/10.11646/zootaxa.4504.2.1
- Shirley, M.H. et al. 2013. Rigorous approaches to species delimitation have significant implications for African crocodilian systematics and conservation, DOI: http://dx.doi.org/10.1098/rspb.2013.2483
- "New crocodile species found hiding in plain sight" by Douglas Main, published in National Geographic.
- Shirley, M.H. 2014. Mecistops cataphractus. The IUCN Red List of Threatened Species 2014: e.T5660A3044332. http://dx.doi.org/10.2305/IUCN.UK.2014-1.RLTS.T5660A3044332.en. Downloaded on 03 November 2018.
- "Mecistops cataphractusAfrican slender-snouted crocodile" by Joel Lavinder and Joshua Pennington, published in Animal Diversity Web.
Thanks for reading!
I hope you enjoyed learning about how the African slender-snouted crocodile is now divided into two species, as well as learning about the extinction threat they are facing (if you can even enjoy that). Thanks for stopping by, and feel free to comment below with any questions or other comments! I appreciate all constructive criticism, so let me know what you think.