Biogeography of Australian Sepsidae (Diptera).

Abstract

Comparison of the distributions of Sepsidae using, inter alia, numerical methods shows that the Australian fauna includes three groups of species: (1) southern temperate (cool-adapted), endemic to Australasia; (2) northern tropical (warm-adapted). also endemic to Australasia; (3) northern tropical widely distributed in the Oriental Region also. Analysis of seasonal occurrence yields a different grouping, two species of Sepsis showing an anomalously early (and still unexplained) peak of abundance in spring. It is considered likely that group 1 above represents stocks that reached Australia well before the Pleistocene, one of them later spreading to New Guinea; species in group 2 originated in or near New Guinea, migrating to Australia in, perhaps, the Pleistocene; and those in group 3 are of Oriental origin, having reached Australia at various times during or since the Pleistocene; some may be quite recent arrivals.