Pearl river stingray

6/1/2019

M. Carvalho

Another freshwater ray? You betcha! Afterall, here at TFUI, we are all about diverse chondrichthyans! For those who don’t know, Chondrichthyans = sharks, skates, rays, and chimaeras.

In 2014, a published paper in the Zootaxa journal formally described two species of freshwater stingray from the Tapajós River in Brazil. Both species were known to the aquarium trade due to their beautiful patterns and coloration. But scientifically, they didn’t really have a name. The first of these species was affectionately known as “P14” or the Itaituba Ray, and the second was usually called the Pearl Ray. The Itaituba Ray, which is now described as Potamotrygon albimaculata for their distinctive white spots, is one of many species of the so-called “black rays” endemic to Brazil. The Pearl Ray, also an endemic to Brazil, is now scientifically known as Potamotrygon jabuti.

Today we are talking about the Pearl Ray, which undoes a beautiful color morphosis as it matures. A dark yellow colour when a neonate, it has dark orange/brown markings that seem to be highlighted by blue-black rings. As it grows older it becomes darker and it soon turns black with golden yellow markings.

As the research paper says, the Tapajós River one of the most diverse areas for freshwater rays and freshwater fish in general. It may be home for 500 species of freshwater fish, and up to 25% of these could be endemic to this region. The Pearl Ray is endemic to the mid- and upper- part of the Tapajós River (known as the Tapajós Rio) and have hexagonal teeth that are perfect for crushing prey with shells. They have dorsal tail thorns in irregular rows and thorns packed close together.

Little else is known about these animals, although the few caught have a size range of 437-810 mm total length (TL). They exhibit matrotrophic viviparity, and usually have two pups per each gestation cycle. We could not find an IUCN assessment of this animal.

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

Artisanal fishery: There is, as yet, no universally-accepted definition; the term is used interchangeably with ‘small scale fishery.’ In general, artisanal fishing will be family-based, employing small or no boats and simple and/or traditional methods.
Bycatch: The part of a fishery’s catch that is made up of non-target species.
Commercial fishery: The activity of catching fish and other seafood for profit.
Crustaceans: Group of animals with a hard exoskeleton, jointed legs and segmented body.
IUCN: International Union for Conservation of Nature.