"The other players who were part of the squad in June but have missed out on selection will continue to be part of the process going forward. We have to build depth because this is a long haul and a tough competition, and they are not out of our plans."
South Africa open their campaign on August 20 against Argentina in Nelspruit and play away a week later in Salta.
The Boks also play Australia and New Zealand home and away in the competition in September and October.
The selection of prop Trevor Nyakane is subject to medical clearance, SARU added.
Springboks squad: Backs: Ruan Combrinck (Lions), Damian de Allende, Juan de Jongh (Stormers), Faf de Klerk (Lions), Johan Goosen (Racing Metro), Bryan Habana (Toulon), Francois Hougaard (Worcester), Elton Jantjies (Lions), Jesse Kriel (Bulls), Lionel Mapoe (Lions), Lwazi Mvovo (Sharks), Rudy Paige (Bulls), Morne Steyn (Stade Francais) Forwards: Lood de Jager (Cheetahs), Pieter-Steph du Toit, Eben Etzebeth (Stormers), Steven Kitshoff (Bordeaux), Vincent Koch (Stormers), Jaco Kriel (Lions), Francois Louw (Bath), Malcolm Marx (Lions), Bongi Mbonambi (Stormers), Teboho Mohoje (Cheetahs), Franco Mostert (Lions), Tendai Mtawarira (Sharks), Sikhumbuzo Notshe (Stormers), Trevor Nyakane (Bulls), Julian Redelinghuys (Lions), Adriaan Strauss (Bulls), Duane Vermeulen (Toulon), Warren Whiteley (Lions)
- AAP