Could this be it? Called a Flauta.
http://www.artemidia.ufcg.edu.br/flautadoce/Flauta%20Eletroacustica.jpg
Looks like it to me. Where can I get one??
Cheers! Richard
They mention whistles, and low whistles and pito de llaves.
According to the web pito de llaves is the cousin to a dulzaina. which is a Spanish double reed instrument in the oboe family
A direct translation is “keyed whistle”
here’s a link to a pito de llaves. sorry if someone already posted, I didn’t read through all the responses.