The former Samoa rugby league worldwide who qualified for England on residency grounds, was one of 15 uncapped players in a 31-man squad named by England coach Eddie Jones for a two-Test series.
The 23-year-old New Zealand-born wing has scored 10 tries in 13 appearances for Sale since joining in December in a cross-code move still being contested by Super League outfit Castleford Tigers.
Hartley became the third England captain in a row to miss out on Lions selection after Chris Robshaw (2013) and Steve Borthwick (2009), and he will be joined in Argentina by the experienced heads of Mike Brown, Joe Launchbury, George Ford, James Haskell and Robshaw who each could claim they were unfortunate not to be going to New Zealand instead.
Captain Hartley, who was a surprising exclusion from the Lions' squad, will lead the Red Rose, while the likes of Launchbury, Ford, James Haskell, Chris Robshaw and Mike Brown will also travel after also missing out on facing the All Blacks.
In the forwards, Underhill (whom Jones has been monitoring for worldwide selection for some time now) Will Collier, Ben and Tom Curry, Nick Isiekwe and Harry Williams will all get the chance to impress the coach.
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Looking ahead to the tour to Argentina, in which England will play Tests in San Juan on Saturday June 10 and in Santa Fe a week later, Jones said: "We are looking forward to going to Argentina and winning 2-0". "We have looked at trying to discover the best young talent in England and see how we can bring them through". "To win the  World Cup we need to have the best and that is our ultimate aim". It's a new squad - half of them don't even know where Dublin is - so it's like starting from day one. He's still got a lot of work to do on his game in terms of position, but they are areas that I think we can work on. "I would like to thank the coaches at Sharks along with the players and backroom staff who have helped me since my arrival and this has helped create this opportunity for me". "If they're not keen to tour they won't play for England again, it's as simple as that", he said. The talent there is just so exciting.
Blues pivot Piers Francis has been fast-tracked into England's squad for June's two-test series in Argentina. "The only thing the senior players should ask of them is to tone it down and find them a steak restaurant at night".
Other than Cipriani, surprise omissions are Wasps hooker Tommy Taylor, Sale number eight Josh Beaumont, Northampton flanker Teimana Harrison, Harlequins wing Marland Yarde and Bath wing Semesa Rokodaguni.
"I'm looking forward to working with the Currys because I want to find out if I can tell the difference between the two of them", joked Jones, who was in the same team at Sydney club Randwick as Australia's Ella brothers.