The Italians will take part in the competition for the first time since 2003 after being pipped to the Champions Cup on the final day of the Guinness PRO12 season, and have been drawn alongside Bayonne, Gloucester and La Rochelle.
Cittadini has just signed up for Top 14 newcomers Bayonne from Wasps and will face Treviso, with whom he spent five seasons.
And with some new opponents this season, Treviso director of rugby Antonio Pavanello is looking forward to the challenge.
He said: "We will do our best and see game after game how we can get on. It will also be a pleasure to be able to face and host at Monigo a former Leone like Cittadini.
"We will take on clubs who we've rarely played before, if not ever. Gloucester are a difficult club who know the tournament well and over time have shown that they give everything in each competition they play.
"In the last four years they have always managed to reach the knock-out stages of the Challenge Cup, winning it two years ago.
"In terms of the French teams, they both have great coaching staffs who will manage the teams depending on the league."
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