One of two bittersweet scarlet aperitivos made by Nardini this was introduced as an alternative to Campari in 1779. It owes its hue to ponceau R4, a derivative...
Other than one would expect considering the word bitter Nardini uses here, this one is closer to Aperol than it is to Campari in respect of aroma and bitterness. Indeed, I can recommend it as a more herbal substitute to Aperol.
Stephan Gröhn