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Africa’s biggest cobra is five species, not one, study finds

One of the two new species, the West African Banded Cobra (N. savannula). Image by Jean-Francois Trape.

  • Africa’s largest true cobra is not one, but five separate species, a new study has confirmed.
  • Two of these species, the black forest cobra (N. guineensis) and the West African banded cobra (N. savannula), are new to science.
  • As a single species, forest cobras were not considered threatened. But with the splitting of the cobra into five species, some species could be more vulnerable to forest loss and bushmeat hunting than others.
  • The occurrence of five forest cobra species also has implications for the development of antivenom to treat forest cobra bites, researchers say.

The highly venomous forest cobra, the largest of Africa’s true cobras, is not one, but five separate species, according to a new study.

At first glance, forest cobras, which can grow to lengths of nearly 3 meters (10 feet) and are frequently kept in zoos, research institutes and private collections, may not look very different. But Wolfgang Wüster, a herpetologist at Bangor University, U.K., and colleagues chanced upon the snake’s potential diversity around 15 years ago by accident.

The team had been working on another species, and had collected some DNA samples of forest cobras from captive collections for comparison.

“To our surprise we found that the mitochondrial DNA sequence differences between [the forest cobra samples] were far greater than between clearly distinct species of other cobras, even though the forest cobras did not appear very distinct visually,” Wüster told Mongabay.

Some populations of the brown forest cobra (Naja subfulva), like this snake from western Kenya, are black and white, complicating their identification. Image by Wolfgang Wüster.

Other researchers were also investigating the possibility of the forest cobra being more than a single species. Luis Miguel Pires Ceríaco, a herpetologist at Villanova University in Pennsylvania, U.S., for instance, found genetic evidence suggesting that the forest cobras on São Tomé Island in the Gulf of Guinea, off Central Africa, were a new species called Naja peroescobari.

To tease apart the snakes’ diversity, Wüster and his team collected tissue samples, including scale clippings, blood, shed skin and liver tissue, from 71 individual forest cobras distributed across Africa. On sequencing their mitochondrial DNA, the team found that the forest cobra could be separated into five candidate species, confirming what previous studies had hinted at.

Two of these species, the black forest cobra (N. guineensis) and the West African banded cobra (N. savannula), are in fact new to science, the researchers report in the study published in Zootaxa.

“The description of two new species to science, especially two cobras of considerable size, is outstanding,” Ceríaco, who was not involved in the present study, told Mongabay.

The large, iconic forest cobra may have evaded taxonomists’ eyes for so long because collecting samples from the venomous snakes can be incredibly hard, Ceríaco added. “We should never forget that these are some aggressive and dangerous animals.”

The Central African forest cobra (N. melanoleuca). Image by Jean-Francois Trape.

While in some cases the different species can be distinguished visually based on patterns and some scale counts, in others, identifying the species can be very difficult.

“For instance, in parts of the Congo, the Central African forest cobra (N. melanoleuca) and the brown forest cobra (N. subfulva) look very similar indeed,” Wüster said in an email. “There is certainly room for more work to find better ways of distinguishing them from external features. However, using DNA to confirm the ID of specimens and to further establish the distribution limits of the four mainland species will be valuable in any case.”

As a single species, forest cobras were not considered threatened. The loss of a few populations in this case wasn’t seen as a major cause for concern. But with the splitting of the cobra into five species, some species could be more vulnerable to forest loss and bushmeat hunting than others, and the loss of some regional populations could even potentially lead to extinction.

The Central African forest cobra and the brown forest cobra, for example, have large distributions with lots of intact rainforest remaining in their ranges, Wüster said. The black forest cobra, on the other hand, could be more vulnerable since it appears to be limited to the Upper Guinean forests of West Africa that have suffered severe deforestation.

“The West African banded cobra (Naja savannula) also seems to be relatively uncommon, and we need more information on its status,” Wüster said. “The São Tomé forest cobra (Naja peroescobari) is probably of the most concern, as it is restricted to the forested parts of a relatively small island, and thus inherently more vulnerable. These findings thus allow us to include these snakes in evidence-based monitoring and management strategies.”

The occurrence of five forest cobra species also has implications for the treatment of forest cobra bites.

“Forest cobras are highly venomous and cause severe health problems to human communities who deal with them,” Ceríaco said. “We know that each species has its own venom, with different biochemical characteristics and effects. Right now we do have some anti venoms for forest cobra snake bite, but with the splitting of this species into five, new research is needed to investigate the venom of each species and develop adequate anti venoms.”

A newly described species, the black forest cobra (N. guineensis). Image by Laurent Chirio.
One of the two new species, the West African banded cobra (N. savannula). Image by Jean-Francois Trape.

Citation:

Wüster, W., Chirio, L., Trape, J. F., Ineich, I., Jackson, K., Greenbaum, E., … & Hall, C. (2018). Integration of nuclear and mitochondrial gene sequences and morphology reveals unexpected diversity in the forest cobra (Naja melanoleuca) species complex in Central and West Africa (Serpentes: Elapidae). Zootaxa4455(1), 68-98.