The distribution and habitat preferences of the Chaoboridae (Culicomorpha: Diptera) of the Holarctic Region

Abstract

Distribution and habitat preferences of species of Chaoboridae in the Holarctic Region are described. Coexistence of larvae of different Chaoborus species in various water bodies reflects differences in geographical distribution, habitat preference, and phyletic relationships. Extant sister species with similar habitat preferences are allopatric whereas those with differences may be sympatric. This suggests that the development of ecological divergence must historically precede coexistence of the immatures of species. Species which coexist often differ markedly morphologically and are not immediately related phylogenetically.Corethrella and Chaoborus (Sayomyia) species that occur in the Holarctic Region and Chaoborus pallidus may have southern, tropical phyletic affinities. Distributions of some North American chaoborids suggest the presence of ecological barriers in northwestern U.S.A. that prevent southern extensions of the ranges of boreal species.