Juan Figallo plays for English club Saracens while the others are all with French teams -- Nicolas Sanchez and Ramiro Herrera (Stade Francais), Facundo Isa (Toulon) and Benjamin Urdapilleta (Castres).
"Some players from abroad have been called up," Ledesma said. "We think they will bring something extra in addition to the players we have here."
Their inclusion marks a move away from the recent policy of selecting almost exclusively home-based players for Argentina’s national squad.
Many of the squad play for the Jaguares, Argentina’s team in the Super Rugby tournament.
Argentina play New Zealand, South Africa and Australia in the Rugby Championship in July and August as part of their World Cup warm-up.
Argentina have been drawn in Pool C at the World Cup and will face France, England, Tonga and the United States.
The tournament begins on Sept. 20 and the final will take place on Nov. 2 in Yokohama.
(Writing by Andrew Downie, editing by Ed Osmond)
