Dragons flanker Jamie Ringer has won two Wales caps

The Newport Gwent Dragons player got the call after Jones broke down in training with an injured left shoulder.

Lions and Cardiff Blues loose-head prop Gethin Jenkins was another shoulder injury victim last week and was replaced by Blues team-mate John Yapp.

Wales also added Dragons back Nathan Brew when centre Gavin Henson withdrew because of fitness concerns.

Ringer, who won his two caps to date on the 2001 tour to Japan, will join up with the tour party after the Dragons' Heineken Cup qualification play-off with Overmach Parma at Rodney Parade on Friday night.

The 30-year-old, whose step-father Paul won eight caps for Wales, has also represented Wales at Schoolboy, Under-21, A and Sevens levels.

Wales coach Gareth Jenkins said: "Jamie has been a consistent performer at regional level and now has the chance to put his hand up for selection for Wales.

"He is replacing one of the squad's more senior players and we are sure he will relish the opportunity to show what he has to offer in the international environment once again."

Nathan Brew has been in outstanding form for the Dragons Wales attack coach Nigel Davies

Jones' withdrawal brings the number of senior Wales players unavailable through injury or rehabilitation to 20.

"Dafydd broke down in training last week and a subsequent scan has revealed the extent of the problem with his left shoulder, which will need repair," said Wales team physio Mark Davies.

The Wales squad departs on Thursday for the two-Test tour of Argentina, with Ringer and five Dragons team-mates due to follow on Saturday after their play-off against Parma.

Ringer, Brew, Luke Charteris, Ian Gough, Hal Luscombe and Rhys Thomas will all be in action for their region on Friday night.

Brew, 23, won his only cap so far in a try-scoring debut against Romania in 2003, while 24-year-old Yapp has never lost in his seven appearances.

"We are looking at players who have the potential to compete for a place in the World Cup squad in 18 months time," said Wales attack coach Nigel Davies.

"Nathan has been in outstanding form for the Dragons in the latter part of this season, after returning from injury, and we have had a good close look at him.

"He is a big, physical lad, an evasive runner and an intelligent rugby player and we are looking forward to working with him.

"He is primarily selected as an outside centre or wing as we've concluded we have adequate cover for the inside centre position vacated by Gavin (Henson) elsewhere in the squad.

"John is also a very competitive player who has shown glimpses of what he is capable of for his region this year."

Yapp gets his chance after Jenkins was ruled out for up to a month with a recurrence of the shoulder problem which required surgery after last summer's Lions tour to New Zealand.

Wales say he has been given an injection "to help settle inflammation" and are confident the 37-cap man will not need further surgery.