The stingray’s identity crisis

For years, locals in Nigeria thought they were dealing with different species of freshwater stingray at the river due to variation in morphology of these species while scientists had reported just one freshwater stingray in the middle belt region of the Niger River.

But, as we continue in search of pincushion rays, the identity crisis arises. In some rivers, the pincushion rays didn’t match what taxonomists had described in terms of size and thorny features, and with further analysis, they turned out to be separate species hiding in plain sight. This other species is the smooth freshwater stingray, also called the Niger stingray, and it had been mistakenly identified as its close relative, the thorny stingray. This mix-up happened because both rays were referred to as freshwater stingrays in Nigeria, and have similar overall shapes. The pincushion ray, known as thorny stingray, has a thick, thorn-studded back, whereas the smooth freshwater stingray has mostly smooth skin and a more rounded disc, but sometimes rough skin that causes the confusion for the locals. So, in places like the middle Niger River around Jebba and Lokoja, many assumed that there were two freshwater ray species when only the smooth stingray was present in those localities. It was a classic case of mistaken identity that only a closer look could resolve.

Solving this identity crisis requires an integrative taxonomy approach that uses multiple tools to identify and differentiate the species. In our research, we combined morphology with DNA barcoding to get definitive answers. This involves measuring body shape and features. At the same time, I took tiny tissue samples for genetic barcoding. Despite the morpho-variations in between individuals, the rays caught in those localities of the Niger River were confirmed to be smooth freshwater stingrays matching the features of museum specimens of that species.  The distinctive thorny pincushion ray, on the other hand, remained exceedingly rare in areas previously reported in Nigeria. In fact, some places where it was assumed to occur turned out to host either the daisy stingray, the Niger stingray or the pearl stingray.

Segun Oladipo performs laboratory procedures for DNA barcoding to genetically characterise stingray species, contributing to species identification and conservation efforts in Nigeria. Photo © Erica

However, in May 2023, as the team was solving the identity crisis, and figuring out the habitat range for the freshwater rays that are known to exist, I stumbled upon a unique stingray with features of the pincushion ray in literatures during a workshop and conservation visit to Kibri, Cameroon. This was recorded in a brackish ecosystem. Historically, the species is known to be present in West and Central Africa waters. The local fishers with historical experience mentioned that the region spanning to Cross River in Nigeria, is known to be a corridor for the species. However, for science, this was a discovery. This discovery brings evidence that F. ukpam does still exist, but is critically endangered. In partnership with conservationists in Cameroon, we will continue our effort to monitor and protect the pincushion ray.

Pincushion ray spotted during a conservation workshop visit to Kibri, Cameroon. Photo © Segun Olayinka Oladipo