The currently recognized Ephemerella species are assigned, as fur as possible, to nine subgenera based on nymphal and imaginal characters. New subgenera are Serratella (type serrata Morgan), Caudatella (type heterocaudata McDunnough), Attenuatella (type attenuata McD.), and Dannella (type simplex McD.); those previously named are Ephemerella Walsh, s.s., Torleya Lestage, Drunella Needham, Eurylophella Tiensuu, and Timpanoga Needham. Thirteen of the species can not be assigned subgenerically without further study.
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George F. Edmunds (1959) studied this question.