As the first notes hit, an audience member picks up the ’60s vibe and starts a cool cat dance in front of the Bunkhouse stage Saturday night. The mood switches, to a ’50s lounge sound, as four-part female harmonies rise and fall, casting a siren spell over a mesmerized crowd. The women onstage should be familiar to Downtown regulars: Heidi Guinn and Summer Soll of The Petals, Chani Leavitt of Rubiks Hotel and Megan Wingerter of A Crowd of Small Adventures. Now they’ve come together, with help from, ahem, male fifth member Jason Aragon (The Clydesdale) to form local-supergroup-of-sorts Dusty Sunshine. “It wasn’t even our idea,” Leavitt confesses. “One day, the Thompson brothers [of Thor at the Bus Stop fame] were like, ‘Hey, why don’t you and Megan start a band with The Petals?’” So they did. Look for them next at Neon Reverb.