Author: (Castelnau, 1855)
FBname: Smooth back river stingray
Remark: A widespread species that may require subdivision. Rosa (1985a) recognizes <i>Potamotrygon dumerilli</i> (Castelnau 1855) and <i>Potamotrygon humerosus</i> Garman 1913 as distinct species, but evidence given is meager. Larger specimens may weigh close to five kg. Reproductive biology studied by Lasso <i>et al.</i> (1997a) in Venezuela; males achieve sexual maturity at 23 cm DL and females at 18.5 cm DL, and females give birth to up to two pups during any time of year. Food consists of fishes, insects and crustaceans. Additional references: Bertin (1939), Sérét & McEachran (1986), Compagno & Cook (1995), Planquette <i>et al.</i> (1996).
Comments: Occurs in stream swamps, floodplain lakes and artificial lagoons.  Feeds mainly on insects and benthic crustaceans (Ref. 27749).