Two new species of tropical freshwater stingray have been discovered in the Amazon basin. The findings, published in the journal Zootaxa, are the first of their kind in over 20 years.
Researchers from the University of Toronto, Scarborough identified the species' distinctive features including "pancake-like" circular bodies and a reduced caudal sting - the poisonous spine the fishes are named after.
X-ray images confirmed that the species both belonged to an entirely new genus - a new group of species that the scientists have named Heliotrygon. There are now four known groups of tropical stringray in South America.
Key differences between the new species include their unique colour patterns. Heliotrygon rosai (above) is light brown or grey in colour with creamy white markings across its surface.
Heliotrygon gomesi (above) is a uniform grey or brown colour. Most of the new specimens were discovered in the Rio Nanay River, near Iquitos in Peru.
"The most important thing this discovery tells us is that there are quite likely to be other large fishes in the Amazon yet to be discovered and described," said lead researcher Dr Nathan Lovejoy.
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