The epandrium and surstyli form an inverted U-shaped structure located ventral to the apex of the abdomen. The surstyli are the ventral, lobelike parts of this structure.There are two pairs, but they are closely associated in Anastrepha and Toxotrypana and appear to be a single pair. The medial surstylus is shorter and bears a pair of toothlike, dark, stout prensisetae. The lateral surstylus is usually longer and varies considerably in shape and length among Anastrepha and Toxotrypana species.