Abstract
Leptocera(ThoracochaetaDuda), a subgenus of sphaerocerid flies associated with marine supralittoral habitats, is revised for the Nearctic Region. Keys are provided for separation of the nine Nearctic species.L. (T.)teskeyi,L. (T.)flaminuta,L. (T.)calminuta, andL. (T.)bajaminutaare described as new andL. (T.)zosteraeis recorded from the Nearctic for the first time. The larvae of three species (zosterae,seticosta, andbrachystoma) are described.