On April 9, Portugal. The Man took its longtime penchant for spontaneity to a new level by recovering from its new drummer’s mid-show departure. As the Alaskan-born, Oregon-based group had done so many times prior, it simply grabbed a member of another act on the bill and winged it. Still, for a band given to extended jamming and thinking on its feet — often, for example, entering the studio on tight deadlines without any prepared material — Portugal. The Man’s propulsive blend of psychedelia, classic rock, ’70s-styled folk-rock and Beatles-inspired harmonies holds together with remarkable cohesion in person. To top it all off, frontman John Baldwin Gourley sets a new precedent for the musical and emotional range that’s possible when a singer delivers vocals exclusively in disco falsetto.