I forgot to mention, I’ve found another reference in the “Manual Oficial” of “Club de Cantineros” of Cuba (1930). In that book the recipe for a Presidente cocktail calls for “vermouth chambery”, but you can also find an ad for “Vermouth Ama”, and the text says: “specially indicated for the making of Presidente cocktail”
One could assume any contradiction (in case Ama is not chambery) would be noticed and corrected, but assumptions sometimes leads to error.
Another assumption would be we’re dealing with a local brand but… grapes in Cuba?
Could be that “Ama” is a defunct chambery brand?
Ama vermouth is mentioned also in the Presidente recipe in the “Recetario Internacional de Cock-tails” of 1937, but a further clue about the lineage of this vermouth could be found in “Libro de Cocktail” by Juan A Lasa (1929) where one can read “1/4 Dolin or Ama Vermouth” in the recipe for that cocktail
Maybe it’s a silly question and everybody knows Ama Vermouth, but I hate to make assumptions. Here are the snapshots from the books and thanks for your kindness