Thank you for your response. Look what I found in the web:
"Echinodorus bleheri.
Comparacion de la forma de una hoja de bleheri (inferior) con una amazonicus. (superior)
Ruben Echeveste; Guadalajara, Jalisco, México."
http://atlas.drpez.org/Echinodorusamazonicus/aac
It says " Echinodorus bleheri.
Comparison between the shape of the leave of the bleheri (below) and the amazonicus (above)."
It definitively looks similar to the leave above.
Bye !
Juan