The South American freshwater stingray often known as the tiger ray in the aquarium trade has finally been formally named by ichthyologists from Brazil, Canada and USA.
Marcelo Carvalho, Mark Sabaj Perez and Nathan Lovejoy describe the ray as Potamotrygon tigrina in a recent issue of the journal Zootaxa.
The authors distinguish the new species from its congeners chiefly by its colour pattern, which consists of a brown or blackish background colour, with a tan, bright yellow or orange irregular, highly convoluted worm-like pattern over the entire disc and tail region, extending to about midway down the tail.
Additionally, the tip of the tail from the sting backwards has alternating dark brown or black and cream bars, which is otherwise only seen in P. schroederi.
Potamotrygon tigrina also differs from some congeners in having a single, short angular cartilage and (usually) two rows of dorsal tail spines that originate relatively far back on tail and with the spines relatively far apart.
The new species has frequently been misidentified as P. menchacai (on the basis of the tail bars thought to be present in this species) in aquarium literature, but a recent study of P. falkneri has revealed P. menchacai to be a junior synonym of this species.
Potamotrygon tigrina has been present in the aquarium trade for at least 13 years, and is known as a difficult species to maintain in captivity.
The new species is known only from the Nanay River, part of the upper Amazon River drainage, although the authors suspect that it is more widespread within the upper Amazon River drainage.
Potamotrygon tigrina is named after its colour pattern on the disc and tail (Latin tigris=tiger).
For more information, see the paper: de Carvalho, MR, M Sabaj Perez and NR Lovejoy (2011) Potamotrygon tigrina, a new species of freshwater stingray from the upper Amazon basin, closely related to Potamotrygon schroederi Fernandez-Yépez, 1958 (Chondrichthyes: Potamotrygonidae). Zootaxa 2827, pp. 1–30.