Great Basin Naturalist


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 ( = 0.56) in S. fidelis and 0.55 µm to 0.69 µm ( = 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.