Distribution Patterns of North and Central American Mayflies (Ephemeroptera)

Abstract

Collection records of North and Central American mayflies were plotted on maps, based on published records, and the distributional limits of species were found to form 24 distinct distribution patterns within 5 larger subdivisions. The Arctic subdivision includes 15 species that occur only above 58° north, and includes two patterns, the Palearctic (Europe) and the Nearctic (North America). The North American subdivision includes 14 species in two patterns that occur almost from coast to coast. The Western North American Subdivision includes 209 species in 9 patterns whose distributional limits are west of the east slope of the MacKenzie, Rocky, and Sierra Madre Occidental Mountains to Jalisco (21°N). The Eastern North American Subdivision includes 373 species in 10 patterns east of the western mountains to Veracruz (21°N). The Mesoamerican Subdivision includes 99 species in 2 patterns, and the distributional limits of most species are from Panama to Jalisco and Veracruz, Mexico. Species occur in only one pattern and one subdivision, except for those that are widely distributed or holarctic, and patterns are composed of only boreal species, or of boreal and austral species, but none are composed solely of austral species.