Having launched his career at Natal Sharks, Geldenhuys played for the South Africa Under 21 side and spent two seasons playing in the Currie Cup with the Pumas before heading to Italy in 2004.
Having qualified to play for Italy on residency grounds, he made his debut for the Azzurri on the 2009 summer tour to Australia and New Zealand and now has 13 caps to his name
"I really didn't expect to be named captain - it is a big surprise," admitted Geldenhuys shortly after the formal announcement by head coach Franco Bernini.
"It's a great opportunity, but also a great responsibility to skipper the team in its first Magners League season. It will be a new adventure with a new team, and a lot of important new players.
"I want our home ground to become a fortress where we can achieve the victories we need. I also want the side to always keep its head up, even after a defeat."
Aironi will launch their competitive career against Munster at Musgrave Park on Saturday, 4 September when they make their debut in the Magners League. Prior to that they will play two friendly fixtures in France and also face Northampton Saints at Franklins Gardens as they prepare for their first season.