Common
Names: Rosette River Stingray, Schroeder's Stingray, Columbian Ray, Sacha
Ray, (and possibly) Chocolate Ray.
Other recorded
names:
Guacamaya-Rochen
- Germany
German
Kukkajokirausku
- Finland
Finnish
Raya guacamaya
- Venezuela
Spanish
Rozetzoetwaterrog
- Netherlands
Dutch
Schröders Stachelrochen - Germany German
Schroeders
Stechrochen - Germany German
Kolumbianischer
Rochen - Germany German
Latin Name:
Potamotrygon schroederi
Family:
Potamotrygonidae
A note on the identification of South American Freshwater Stingrays. Dorsum patterns and colors are extremely variable
among the freshwater rays of South America making positive identification using
pattern and coloration alone extremely difficult. Some morphologically different
species occasionally display an almost identical pattern and to make
identification even harder there can be a degree of hybridization among
sympatric species. Important characteristics to help the observer overcome these
problems include the lateral markings on the tail, the presence or lack of
raised denticles along the tail, the ratio of tail length to disc length, and
the size and position of the eyes (although this last characteristic changes
with age).
Identification:
An extremely variable species even compared to other river stingrays. Some
specimens exhibit clusters of spots that form flowerlike patterns on a plain or
subtly mottled background. Flower patterns become smaller and more uniformly
circular toward the edge of the disc. Other specimens display a dark reticulated
pattern enclosing irregularly shaped light spots. There are endless intermediate
color morphs. The tail is always patterned with distinct and regularly spaced
dark bars. This is an important factor in positive identification.
Size: Maximum disc
width 60cm
Habitat:
South American river basins.
18-25 degrees C.
Abundance
and distribution: Columbia to Brazil. Rio
Apure (Orinoco basin) and Rio Negro (Amazon basin) and Rio Uaupes (northern
Brazil) among others. Originally described from Venzuela (boca Apurito, Rio
Apure).
Behavior:
Reproduction:
Matrotrophic viviparity.
Observations:
Similar
species: Where to start...
Potamotrygon schroederi may be confused with many other South American
river stingrays. It differs from P.yezepi in having regularly spaced bars
along its tail. It can be distinguished from P.humerosa and
P.dumerilii in having dark centers to its spots. P.scobina is also
superficially similar but generally has more uniformly rounded markings.
Reaction
to divers: Unknown but some South
American freshwater rays are known to act
aggressively when threatened. River
stingrays are responsible for many injuries to wading fishermen.
Diving
logistics: There are currently no organized opportunities to interact with
freshwater stingrays but aquarist collecting sites include Paraguay, Peru, and
Brazil.
Other
diving locations submitted by readers:
References
and further reading:
Aqualog Freshwater Rays. Richard Ross &
Frank Schafer
Sharks and Rays Elasmobranch guide to the
World. Ralf M. Hennemann IKAN
Fishbase.com
