In 2011, researchers discovered two new species of freshwater stingrays in the Amazon River.
The Heliotrygon (rosai and gomesi), commonly referred to as the Pancake stingrays, is the first new genus of stingrays from the Amazon described since 1987.
In the equatorial forests, the average monthly temperature exceeds 18 °C (64 °F) all year round and the average annual rainfall is no less than 1,680 mm.