Argentina travel to Chile on Saturday before hosting Uruguay on July 8, while Uruguay and Chile then face each other a week later.
Argentina go into the tournament as hot favourites having beaten Wales 2-0 in their recent series before narrowly losing to New Zealand last Saturday.
Felipe Contepomi is not included in the Pumas squad.
The team which wins the South American Championship will go on to play in Group D of the World Cup in 15 months' time, alongside France, Ireland, the African champions and a third European qualifier.
The second-placed side will go into a play-off against the winners of the qualifying group between the USA, Canada and the top Caribbean qualifier.
Argentina squad for South American Championship:
Forwards: Pablo Bouza (Harlequins), Martin Durand (Montpellier), Juan Manuel Leguizamon (London Irish), Martin Schusterman (Plymouth), Rimas Alvarez (Perpignan), Marcos Ayerza (Newman), Manuel Carizza (Biarritz), Gaston De Robertis (Regatas Bella Vista), Pablo Gambarini (CASI), Agustin Guzman (Tucuman RC), Mario Ledesma (Montferrand), Martin Scelzo (Montferrand).
Backs: Agustin Pichot (Stade Francaise), Gonzalo Tiesi (London Irish), Miguel Avramovic (Alumni), Lucas Borges (Stade Francaise), Rafael Carballo (Toulon), Juan de la Cruz Fernandez Miranda (Hindu), Hernan Senillosa (Montferrand), Federico Serra (SIC), Federico Todeschini (Beziers), Nicolas Vergallo (Jockey Club Rosario).