You’ve heard of Marcel Duchamp’s Nude Descending a Staircase? Meet John Singer Sargent’s Man Fully Clothed Operating an Elevator. Thomas Eugene McKeller—a Black man—was on the job at Hotel Vendome in Boston when he caught the eye of Sargent, who portrayed him as any number of Greek gods and goddesses in murals at the city’s Museum of Fine Arts. This provocative Pygmalion saga, first publicized in the recent exhibition “Boston’s Apollo” at the Isabella Stewart Gardner Museum, now assumes operatic life in American Apollo, a 20-minute chamber opera commissioned for the Washington National Opera’s young-artists program. In anticipation of a full-length version to premiere at the Des Moines Metro Opera two years from now, the company presents just the torso, featuring Justin Austin as McKeller, Thomas Glenn as Sargent, and Mary Dunleavy as Gardner, Sargent’s munificent patroness. A lecture by the Gardner Museum’s Nathaniel Silver complements the brief musicale. —Matthew Gurewitsch