The 20-year-old touched down in the 22nd minute after his elder brother had crashed over in the fifth, and in doing so the duo became the first siblings since Gavin and Scott Hastings at the 1995 World Cup to score in the same international for Scotland.
And despite having both represented GUINNESS PRO12 high-flyers Glasgow during their careers, the pair had never played along each other professionally.
"It's hard to put into words what happened on Saturday," Jonny told the Scottish Daily Record.
"But it was a very special day and a proud moment for all the family.
"It was a great win against a strong Argentina side and to run out with my brother at BT Murrayfield is something I'll never forget.
"Just being named in the team with Richie was amazing, never mind both of us scoring a try, so it's all pretty surreal.
"People said to me one day we would play together but I always laughed it off and never really thought it would be the case, so it's pretty amazing.
"Richie's always been there for me when I was younger and he's been a great role model for me, from the way he trains to his diet.
"Growing up watching him for so long I know how hard he had to work to get where he is now and that inspired me to do the same."
Vern Cotter confirmed both brothers will start again this Saturday against the All Blacks as he keeps his faith in the same XV, dominated by players in the GUINNESS PRO12, that triumphed last weekend.
And Jonny knows the size of the test facing the Scots.
He said: "There's a real team environment and I'm honoured to be a part of it at the moment.
"But the way we conceded in the second half was disappointing and we need to work hard to fix what went
wrong for the world champions coming this weekend.
"We will have to play better because Saturday will be a big step up and it's going to be really tough."
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