Potamotrygon tigrina

A newly named Potamotrygon tigrina—or tiger ray—swims in the Amazon River Basin.

Photograph courtesy Oliver Lucanus

  
An Amazon stingray known as the tiger ray has finally earned its scientific stripes: It's been officially recognized as a new species.
For more than a decade, aquarium traders in the upper Amazon River Basin of Peru have caught the freshwater fish, whose name—Potamotrygon tigrina—is inspired by its orange-black coloration and banded tail.
Up to 31 inches (80 centimeters) wide, the species is distinct from other stingrays based on, among other features, its conspicuous colors and its tail spines, which are lower and not as closely grouped as those of its relatives.
(See related pictures: "Odd Stingless Stingrays Discovered in Amazon.")

"It's one of the prettiest species," said Marcelo de Carvalho, a zoologist at the University of São Paulo in Brazil who led a new study on the tiger ray.
Tiger Ray's Patterns a Mystery
Why P. tigrina is so striking compared with the bland browns and tans of other stingrays is still a mystery, de Carvalho added.
For instance, the stripes could be warning coloration—although most Amazon freshwater stingrays have few predators, other than the occasional crocodile.
"It's kind of ungainly to fit into the mouth of another fish," he said.
Overall there's virtually nothing known about the tiger ray—in fact, aquarium traders who catch them in the wild or breed them in captivity probably know much more about their biology than most scientists, he added.
P. tigrina is one of the most popular types of pet rays in Asia, especially in Japan and China. (See a giant freshwater stingray caught in Asia.)
Giving the animal a formal species classification "is the first step in understanding how we can regulate this resource," de Carvalho said.
The tiger-ray study appeared April 21 in the journal Zootaxa.

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