Couplet 116

116a:  Prosternal intercoxal process complete, reaching behind fore coxa to level of mesosternum; posterior portion of hypomeron not extending behind fore coxa; elytral epipleuron with an internally carinate edge complete to suture; head with face narrowed; clypeal margin straight; 3 basal ventrites connate

Psephenidae   p. 420

115b:  Prosternal intercoxal process incomplete, not reaching beyond midpoint of fore coxa; posterior portion of hypomeron variable behind fore coxa; elytral epipleuron narrowed before reaching suture (complete in 1 genus); head with face not greatly narrowed; clypeal
margin emarginate; all ventrites free