LOST TROPICS | The Brazilian tropicalia band OS MUTANTES wrote their self-titled record in the late 1960s, when their members were between the ages of 17 and 21. It was wild, fusing traditional Brazilian pop with the newly-emergent clatter of Western rock and roll to form an eerily, effortlessly psychedelic sound with serious pop highs. They split in the ’70s, but reformed last decade, presumably when the Internet helped to catapult their early records from cult classics toward canonization. They reformed in 2006, but the effort quickly turned from revival tour to a fully invigorated new band. They do a much different thing now, but not any different than any group would be after 45 years. Os Mutantes play with CAPSULA and local faves FOAM CASTLES at SPACE Gallery, 8:30 pm; $18-22. 538 Congress St., 207.828.5600.