Kyle Rowe, the uncapped London Irish wideman, and Duhan van der Merwe, the Worcester wing, were both unable to join the camp at the Oriam due to illness.
Bath back-row forward Josh Bayliss was also not involved because of concussion.
Maitland, 33, has scored 15 tries in 53 appearances for Scotland.
He was a key member of Townsend’s Six Nations squad last season, and was particularly impressive in the win over England at Twickenham. He also played in the narrow home defeat by Ireland and the home win over Italy. He missed the final match against France in Paris because the rearranged game fell outside the international window and Scotland were limited as to how many English-based players they could pick.
He scored a try at the weekend in Saracens’ 45-24 win over London Irish in the European Challenge Cup.