An unpublished, unperformed and previously unknown composition by Richard Strauss, the first major 20th-century musical discovery in more than a decade, was sold here today at Sotheby's for $61,000. Its buyer was not identified.

Titled "Malven," after the German flower of the same name, the original manuscript for the short song was discovered earlier this year among the personal belongings of the late Czechoslovak soprano Maria Jeritza. It was composed shortly before Strauss died in 1949 and inscribed, in the composer's hand, "To the beloved Maria, this last rose."

Richard Strauss, one of the major German composers of this century, is best known for highly romantic opera scores, including "Don Quixote" (1898), "Salome" (1905), "Elektra" (1910) and "Der Rosenkavalier" (1911). He also composed more than 100 songs. "Malven," with lyrics by the Swiss poet Betty Knobel, is probably the last song and composition he wrote.

Jeritza, noted for her creation of the part of Adriane in the Strauss opera "Adriane auf Naxos" in Vienna in the early 1900s, remained his favorite soprano, and according to some biographers, his mistress, for the duration of his career. She appeared in revivals of many of his earlier operas and in the first performances of the later ones; she was the first to perform the second act of "Tosca" lying down.

"Malven" was written especially for Jeritza, according to the romantic letter accompanying the manuscript. In the letter, Strauss also thanked Jeritza for gifts. Following persecution and eventually exile at the hands of the Nazis, Strauss immigrated to Switzerland in 1944. Jeritza and her husband, Irving Seery, a Newark umbrella manufacturer, supported Strauss during his last years.

No one knows for sure why Jeritza kept the manuscript to herself. New York Times critic John Rockwell has speculated that she had lost most of her vocal powers by 1948. To have performed the song in public may have been an ordeal she could not face.

Sotheby's discovered the manuscript during a dinner conversation in London last Christmas. Richard Blackford, a young British composer who had recently completed a feature-length documentary on the life of Strauss, mentioned to David Redden, head of Sotheby's book department, that he would like to get his hands on a mysterious Strauss manuscript.

Blackford had heard about the manuscript from Strauss' daughter-in-law and even knew that it had been given to Jeritza. Redden contacted the lawyers handling Jeritza's estate, and after several months of negotiations, finally received "Malven" to sell.

There was one problem. Since the Strauss heirs retain copyrights to all of his work, published or unpublished, performed or unperformed, known or unknown, the manuscript was sold without those rights.

"Yes," said Redden, "if we had the rights to sell, perhaps the price would have been higher. But you must remember that no one has heard this piece either. I cannot even hum a few bars."