The larval stage of Heptagenia adaequata (Ephemeroptera: Heptageniidae)

Larvae of the poorly known western North American species Heptagenia adaequata are described for the first time based on material reared from the Saskatchewan River system. Diagnoses are provided for differentiating larvae of H. adaequata from other species of Heptagenia within its range, especially the common H. solitaria and H. elegantula, with which it might be confused.