Southeastern Caddisfly Fauna: Origins and Affinities

Abstract

About 40% of the 1369 Nearctic caddisfly species occur in the southeastern portion of North America, with 12% being endemic to it. Using techniques of cladistic historical biogeography, generalized tracks were found among Trichoptera species that link the Southeast with areas outside of the continent and with areas elsewhere in the Nearctic Region. A few tracks are known internally among the major southeastern areas of endemism, but none are sufficiently well corroborated to be considered generalized. Intercontinentally, the most recent generalized tracks are with the Eastern Palearctic, Neotropical, and Western Palearctic areas of endemism. At least 16 species occur exclusively in both the southeastern part of the Nearctic Region and the Neotropical Region, suggesting a greater modern bio-continuity between these areas than with other intercontinental regions. Within North America, the Southeast is most properly considered a subset of the Eastern Nearctic area of endemism or, on a more refined scale, as a mosaic of at least three areas of endemism. The biota of the Southeastern Coastal Plain, especially, probably has experienced many episodes of cosmopolitanism and vicariance through time.