A spokesman for the opera in London’s Covent Garden confirmed on Sunday that Voigt had been dropped from the lead role in a summer 2004 production of Richard Strauss’ “Ariadne on Naxos” and that the reason was her size. The spokesman, Christopher Millard, said Sunday that casting director Peter Katona had selected a black evening dress for the part and believed Voigt would not look right in it.” Still, says the company, Covent Garden hopes Voigt will consent to perform there again in the future