Gloucester fly-half Adam Hastings and Bath number eight Josh Bayliss return to the squad after being ruled out recent squads through injury.
Hooker Dylan Richardson made his Scotland debut in 2021 against Japan as a back-rower but has since changed position and recently lifted the Challenge Cup with Sharks, coming off the bench in the final in London.
He is an option at hooker, alongside the Edinburgh duo Ewan Ashman and Patrick Harrison and Northampton’s Robbie Smith – with the latter two both uncapped.
Townsend says a desire to create more competition for the Scotland number two jersey is the reason for the surprise omission of in-form Glasgow Warriors hooker Johnny Matthews from the squad.
Matthews has played a key role in Warriors’ run to the URC semi-finals and has scored 17 tries in his last 25 matches.
“I think with Johnny and Dave Cherry, they’ve been in our environment and we feel with where we are with hookers, we want to give an opportunity to younger players to really put their hands up for selection in the future,” Townsend told the BBC Scotland Rugby Podcast.
“This gives us an opportunity to see three of our younger hookers or players that are coming through in that position.
“On a tour where Ewan Ashman will be the leading hooker, he’s played very well for Edinburgh this year, so yes we could have taken Johnny, we could have taken Dave, but we decided to look at players that haven’t been involved in our environment.”
Townsend also insisted George Turner still had an international future despite the hooker not being named in the squad and heading to play for Kobe Steelers – but acknowledged it will be “challenging” for the 31-year-old to represent Scotland while playing in Japan.
Edinburgh flanker Jamie Ritchie, currently on 49 caps, and Glasgow centre Huw Jones, who has one less, could reach their half-century milestones on tour.
Three development players – prop Fin Richardson, who has signed for Glasgow Warriors next season, Glasgow scrum-half Ben Afshar and Edinburgh lock Rob Carmichael – will join the squad as a learning opportunity and to bolster training for the final two weeks.
Scotland will play the Canadians in Ottawa on 6 July before journeying to Washington to take on USA six days later.
Chile are their hosts on 20 July before Townsend’s squad head to face Uruguay a week later.