Key to species of male Cyrtusa of the continental United States and Canada

1. Aedeagus (Fig. 1) with median lobe broad; parameres short, with only membranous apices extending beyond median lobe. Widespread Holarctic species...................... C. subtestacea Gyllenhal

– Aedeagus with median lobe slender; parameres large, elongate, with apices extending beyond median lobe. California and Oregon ........................................... C. grossepunctata Daffner