In an unusual recital at the Pan American Union last night the Ecuadorian soprano Beatriz Parra coupled songs in her native Spanish with Russian songs. It was a colorful and highly personal choice, reflecting the singer's heritage and her studies in Moscow at the Tchaikovsky Conservatory.

For a program so heavily weighted on the emotional side it worked surpsingly well because it suited Parra's big voice and passionate nature. However, the evening would have been even more satisfying if she had occasionally resisted the temptation to pull out all the stops.

In particular, the first half devoted to the songs of Glinka, Tchaikovsky and Rachmaninoff would have benefited from greater restraint in the use of her considerable resources. Her rich and vibrant sound would have been even more effective if matched with greater variety in coloring and more rhythmic flexibility.

That she can impart a strongly individual flavor to a song was made abundantly clear in Parra's Spanish selections. With a keen sense of timing and color she succeeded in making a distinctive scene of each song by Guevara, Rodrigo and Turina.

A special audition to the program was a series of flowing, melodic songs by her accompanist Jaime Leon, director of the Colon Theater of Bogota and former music director of the American Ballet Theater. In these selections and all the others he was an exceptionally adept and sensitive accompanist.