It is an understatement to say that tradition lay behind the Teatro di San Carlo's performance of ''La Serva Padrona'' on Monday evening at the Mark Hellinger Theater. After all, the opera company, which presented Pergolesi's comedy as the first offering in an Italy on Stage festival, comes to us from Naples, where the intimate two-scene comic opera, technically known as an intermezzo, was first given 254 years ago.
The Mark Hellinger, though acoustically dry and somewhat too large (1,603 capacity) for so modestly charming a piece, nevertheless put one in an appropriate mood with its rococo decor. The staging, similarly apt in some respects, placed a string orchestra on a platform at the audience's eye level. The 13 musicians and their conductor, Herbert Handt, all bewigged and dressed in 18th-century costumes, sat amid billowing clouds made of wooden cutouts. Between scenes, liveried lackeys served Italian ices to the musicians and to selected members of the audience, presumably reflecting operatic custom in Pergolesi's day. On still another plane, on a recessed stage above the orchestra, a cast of four played out the story of the dominating young maid who runs her master's life and eventually tricks him into marrying her. All this decorative fancy and staging manipulation seemed unduly precious at times, but no doubt the director felt the air of period playfulness was necessary to enliven an essentially static piece for a modern audience.
''La Serva Padrona'' was translated in the program book as ''The Mistress Maid,'' though ''The Servant as Mistress'' might come closer. Originally, it was performed as comic relief between acts of Pergolesi's own highly serious ''Prigioniero Superbo,'' now only a footnote in history. ''La Serva Padrona,'' however, lives on as one of the foundation works in the comic-opera tradition that was to climax with Mozart. Time and time again, the music seems to prefigure familiar passages from Mozart's operas (Sarastro makes a wraithlike appearance in Uberto's final aria, for instance), which is striking in view of the fact that Pergolesi died 20 years before Mozart's birth. The more we know about 18th-century opera, the more we realize how shrewdly Mozart used the common musical coin of his time.
Pergolesi's masterly little intermezzo, perfectly balanced in the 18th-century tradition with two dovetailed arias and a duet in each scene, offers singing comedians grand opportunities. The San Carlo performance, quite adequate vocally if not of top international quality, did not try to bloat this small masterpiece out of proportion. In the two singing roles, Valeria Baiano as the spunky Serpina and Silvano Pagliuca as her wealthy victim Uberto extracted a great deal of humor from the ancient tale with a minimum of slapstick. Virgilio Villani, the mute servant and accomplice of Serpina, strutted wittily in Scaramouche disguise as the terrible swordsman, Capitan Tempesta.
Miss Baiano's slender, colorless soprano could not make the most of her most famous aria, ''Stizzoso, mio stizzoso,'' but otherwise she nicely conveyed the lovable bossiness that Uberto finally could not resist. Mr. Pagliuca, an accomplished buffo actor, wisely found a semiserious tone for Uberto's touching second-scene aria, ''Son imbrogliato io gia.'' The orchestra, under Mr. Handt's discreet direction, sounded surprisingly tentative and in need of that refreshment break between scenes.