Leading American Ballet Theater Soloist Peter Fonseca, 28

Peter Fonseca, a leading soloist with the American Ballet Theater much heralded for his interpretations of the 19th-Century Danish choreographer August Bournonville, is dead at the age of 28.

A family spokesman said he died Saturday in Wheaton, Md., after what was described only as a lengthy illness.

Fonseca joined ABT in 1976 and, with Susan Jaffe, Cheryl Yeager and Robert La Fosse, was quickly pushed into leading roles by artistic director Mikhail Baryshnikov. Fonseca’s career took a particularly fortuitous turn when he hastily had to fill in for an injured male lead dancer in “Don Quixote” in 1979. The New York Times said several years later that Fonseca “showed signs of the speed, lightness and clarity that characterize his work today.”

Fonseca trained under his mother, Hortensia, at the Washington Academy of Ballet in the nation’s capital and performed with the Ballet Theater Repertory Company before joining the parent group. He credited his mastery of Bournonville’s demanding style to his training in the junior company.

Recently he had toured nationally in ABT productions of “Rendezvous,” “Theme and Variations,” “Undertow,” “Prodigal Son,” “Coppelia,” “Raymonda” and “La Sonnambula.”

In addition to his mother, he is survived by four brothers.