MacArthur will be in a Scotland match-day 23 for the first time after his Warriors team-mate, Dougie Hall, was ruled out through the knee injury he sustained against England.
And the 25-year-old Glasgow Warrior could not hide his delight at the news. “It’s a huge honour to have the chance to play for my country,” he said.
“It’s something I’ve dreamed about since I started playing mini rugby at Ayr and aimed for since I became a professional with Glasgow Warriors.”
Meanwhile, flanker Alasdair Strokosch, who suffered an eye injury in last weekend’s defeat by England, is expected to be out of action for four weeks.
Scotland team doctor James Robson said: “Alasdair was seen by a specialist at the Spire Murrayfield Hospital this week and the injury was diagnosed as a fracture of the orbital floor [the area around the eye].
“Alasdair is returning to his club in France and will be in their care. If he has no complications he should be available to return to action in four weeks’ time.”