The male epiprocts of 2 closely related western Nearctic species, Sweltsa fidelis (Banks) and S. revelstoka (Jewett), were examined using SEM. The males of these 2 species have been historically distinguished by epiproct measurements. The ratio of the length from the base to greatest width versus total epiproct length ranges from 0.49 µm to 0.67 µm (x̄ = 0.56) in S. fidelis and 0.55 µm to 0.69 µm (x̄ = 0.60) in S. revelstoka. Similarities in measurement suggest that the location of the greatest epiproct width is not a reliable and consistent character for distinguishing males of these 2 species.
Delk, Jennifer K.; Kilgore, Mary Jane; and Stark, Bill P.
"Comparison of the epiproct structure of two closely related species, Sweltsa fidelis (Banks) and S. revelstoka (Jewett) (Plecoptera: Chloroperlidae),"
Great Basin Naturalist: Vol. 58
, Article 8.
Available at: http://scholarsarchive.byu.edu/gbn/vol58/iss3/8