Wales summer tour: Ellis Jenkins and Cory Hill named co-captains
Cory Hill and Ellis Jenkins will co-captain Wales on their summer tour.
Wales will play South Africa in Washington, USA, on 2 June before two Tests against Argentina.
Cardiff Blues scrum-half Tomos Williams is the only uncapped player in Warren Gatland's 31-man squad, while Scarlets wing Tom Prydie returns after a five-year international absence.
Wales captain Alun Wyn Jones is rested to ensure the lock is fit for the 2019 World Cup in Japan.
Hill, George North, Ross Moriarty, Tomas Francis and Gareth Davies are the only 2017 British and Irish Lions named in the squad, with the others rested after a long season.
Veteran lock Luke Charteris returns to the squad having last played as a replacement in the 2017 Six Nations match against France in March.
"He is a player we have discussed and not been involved for a while now," head coach Gatland said.
"He has not been out of thoughts in term of a World Cup spot. We wanted to send a message that he is still in our thoughts.
"He has not played a lot of rugby and not been involved at all. We wanted to give him this chance and assess where he was and put him in a position hopefully with World Cup selection."
Prydie became the youngest cap in Wales' history at 18 years and 25 days when he started on the wing against Italy in March 2010, and the youngest try scorer at 18 years and 102 days against South Africa the following June.
He has not played for his country since the 2013 summer tour to Japan, but the Scarlets back is now in line to add to his five caps.
"We have been pleased with Tom this year at the Scarlets and he played well last weekend," Gatland said.
"He has had a few injuries. We picked him as a young player and he was unlucky with injuries and missed out on opportunities.
"He is 26 now and has genuine pace. You just feel that to see where he is at.
"There are a couple of younger players knocking on the door and we did not want to throw him on the scrap heap and we wanted to pick him on this tour and see where he is at.
"The next 12 months could be important for him to be in contention for the World Cup."
The Springboks have lost their past two meetings with Wales, both in Cardiff, but a neutral venue in the US capital awaits for their tour opener.
"It will be a unique experience and something we have not done before," Gatland said.
"I will be looking forward to having a different crowd and different atmosphere and being in a city we have not experienced before.
"It will be great for this group of players and take them out of their comfort zone and we will experience that in Japan 2019."
Wales have won five out of the last six meetings against the Pumas, all at the Principality Stadium, but it is a different story on their home soil, with Argentina winning three of the last four Tests against Wales in 2004 and 2006.
The visitors' last tour series win against the Pumas came in 1999, when Wales were captained by now assistant coach Rob Howley.
"This summer is a great opportunity for this squad to build on their experience, get Test match game time under their belt and face Rugby Championship opposition," said Gatland.
"We have picked a squad of 31 to try and give players as much game time as possible.
"It shows the depth we have built in recent years that we have just one uncapped player in the squad in Tomos, but he has been in a number of squads so knows the environment well."
Forwards: Rob Evans (Scarlets) (25 Caps), Wyn Jones (Scarlets) (8 Caps), Nicky Smith (Ospreys) (18 Caps), Elliot Dee (Dragons) (7 Caps), Ryan Elias (Scarlets) (2 Caps), Tomas Francis (Exeter Chiefs) (31 Caps), Samson Lee (Scarlets) (38 Caps), Dillon Lewis (Cardiff Blues) (2 Caps), Adam Beard (Ospreys) (2 Caps), Bradley Davies (Ospreys) (62 Caps), Seb Davies (Cardiff Blues) (4 Caps), Luke Charteris (Bath) (74 Caps), Cory Hill (Dragons) (15 Caps) (Co-Captain), James Davies (Scarlets) (1 Cap), Ellis Jenkins (Cardiff Blues) (6 Caps) (Co-Captain), Ross Moriarty (Gloucester) (20 Caps), Josh Navidi (Cardiff Blues) (11 Caps), Aaron Shingler (Scarlets) (17 Caps).
Backs: Aled Davies (Scarlets) (8 Caps), Gareth Davies (Scarlets) (32 Caps), Tomos Williams (Cardiff Blues) (*uncapped), Gareth Anscombe (Cardiff Blues) (15 Caps), Rhys Patchell (Scarlets) (8 Caps), Hadleigh Parkes (Scarlets) (6 Caps), Owen Watkin (Ospreys) (4 Caps), Scott Williams (Scarlets) (55 Caps), Josh Adams (Worcester Warriors) (2 Caps), Hallam Amos (Dragons) (15 Caps), Steff Evans (Scarlets) (9 Caps), George North (Ospreys) (73 Caps), Tom Prydie (Scarlets) (5 Caps).
2018 summer tour schedule
Saturday, 2 June
South Africa v Wales (Robert F. Kennedy Memorial Stadium, Washington, USA)
Saturday, 9 June
Argentina v Wales (San Juan del Bicentenario Stadium, San Juan)
Saturday, 16 June
Argentina v Wales (Estadio Brigadier López, Santa Fe)