Chris Paterson has been replaced as Scotland captain with Edinburgh team-mate Scott Murray stepping into the breach for the tour to Australia, Samoa and New Zealand.
Murray captained the Scots in the pre-World Cup Tests against Italy and Wales last year.
Paterson, appointed when Matt Williams took over from Ian McGeechan as Scotland coach, is demoted to vice-captain alongside Gordon Bulloch, Mike Blair and Tom Smith.
Williams, who failed to win a game in his debut RBS 6 Nations campaign, told www.scottishrugby.org: "This decision is no reflection on Chris Paterson.
"I said we would be moving the captaincy around and Mossy (Paterson) has done a fine job and has moved forward as a leader."
Saracens centre Robbie Kydd is the major surprise among the 12 uncapped players in the squad.
But Williams is convinced the 22-year-old Auckland-born player, who qualifies through a father from Montrose, can prove himself for the future.
Williams said: "With the retirement of so many backs since the last World Cup we have been casting our net wider in the search for Scottish players.
"Robbie is currently playing in the Premiership and this tour is about development.
"His age puts him in the right bracket for Rugby World Cup 2007 and he can also play full-back or stand-off."
Prop Joel Brannigan, centre Stephen Cranston, back-row forward Scott Gray, locks Craig Hamilton and Alastair Kellock, wing Sean Lamont, lock Scott Macleod, centre Graeme Morrison, full-back Gareth Morton, prop Euan Murray and wing Hugo Southwell are all uncapped at senior level.
Williams added: "The point about this tour is that it is part of our four-year plan that we devised last August to take us towards the next World Cup.
"This is our big tour of this four year period. Next season there is no tour - simply a fixture against Romania.
"Remember, too, that the tours are part of the IRB schedule and there is an obligation on us to undertake them."
Ten players in the party will return home after the midweek fixture against New South Wales and before the two Tests against the Wallabies.
As well as earning the Scotland captaincy, Murray has been named the Famous Grouse Player of the Season for the third time.
Scotland squad to tour Australia and New Zealand in the summer:
R Beattie (Gwent Dragons), G Beveridge (Glasgow), M Blair (Edinburgh), J Brannigan (Edinburgh), G Bulloch (Glasgow), S Cranston (Borders), C Cusiter (Borders), S Danielli (Bath), M Di Rollo (Edinburgh), B Douglas (Borders), I Fullarton (Sale Sharks), S Gray (Bath), S Grimes (Newcastle), A Hall (Glasgow), C Hamilton (Newcastle), A Henderson (Glasgow), B Hinshelwood (Worcester), A Hogg (Edinburgh), A Jacobsen (Edinburgh), A Kellock (Edinburgh), R Kydd (Saracens), S Lamont (Glasgow), D Macfadyen (Glasgow), C Mather (Glasgow), S Macleod (Borders), G Morrison (Glasgow), G Morton (Borders), E Murray (Glasgow), S Murray (Edinburgh), D Parks (Glasgow), C Paterson (Edinburgh), J Petrie (Glasgow), T Philip (Edinburgh), G Ross (Leeds), R Russell (Saracens), S Scott (Borders), T Smith (Northampton), H Southwell (Edinburgh), S Webster (Edinburgh), J White (Sale Sharks).