Matt Mustchin has admitted his surprise at finding himself in the Scotland touring party for the trip to Argentina.
The Edinburgh forward is in Frank Hadden's pool for the two-Test tour against the Pumas, who knocked Scotland out of last year's World Cup at the quarter-final stage.
Mustchin only qualified for Scotland this week on residency grounds on the third anniversary of his move to the capital.
He is in line for a place on the bench at least with Scotland battling a dearth of locks due to Scott Murray and Nathan Hines' involvement in the on-going French championship.
Jim Hamilton is injured so Craig Hamilton has also been called up to join Mustchin, Alastair Kellock and Scott MacLeod in the squad.
Mustchin said: "It was a surprise to be considered for a call-up to the Scotland squad because I hadn't really ever thought about it at all.
"So then to be asked was a huge honour for me. Andy Robinson asked me about my feelings towards a possible call-up the week of the Scarlets match; he sat me down and asked me if I would be interested.
"I went away and spoke to a few different people, whom I trust and respect, about it and within two or three hours they had reinforced my own first impression that it was too good to pass up and that it would be a huge honour.
"I never ever thought this would happen; it didn't even ever cross my mind at any stage that I could become an international player."
Scotland play Argentina on June 7 in Rosario and seven days later in Buenos Aires.
England Under-18 head coach John Fletcher insists his young side will be better for the experience after beating Italy in the bronze final to round out their 2015 Rugby Europe U18 Championship campaign in style.