The exquisite outdoor amphitheater at Untermyer Gardens will host a benefit performace at 5 PM Sept. 19 by the Parul Shah Dance Company, which will present various aspects of the Kathak repertory.  Dancers are Mohip Joarder, Sumika Rajguru, Jin Won, and Parul Shah, accompanied on sitar and tabla.  The performance will be preceded by tours of the garden at 4 PM and followed by a wine reception with Indian canapes at 6 PM.  Proceeds from the benefit will support efforts to maintain and restore the garden, which is home to the finest Indo-Persian garden in the western hemisphere.