Annotated records of blackfly (Diptera : Simuliidae) distribution in southern Africa

Regional and catchment distributions of blackflies Diptera: Simuliidae) in southern Africa are presented and discussed relative to the biology and env ironmental preferences of the aquatic stages. Distribution data are based o n all known records, both published and unpublished. Thirty nine blackfly s pecies are recorded: 13 are widespread with no particular geographical affi nities, 18 are restricted in distribution and eight are rare. Distributions are closely related to downstream changes in rivers, although eight specie s are endemic to parts of the southern and southwestern Cape, while eight a re absent from the southern and southwestern Cape. The most common and wide spread species are Simulium nigritarse s.l. Coquillett, S. medusaeforme Pom eroy, S. damnosum s.l. Theobald and S. adersi Pomeroy, all of which are ass ociated with medium-sized rivers, and all of which are likely to be species complexes. Seven species occur in large rivers, three of which are restric ted to large rivers. A further six species were recorded in temporary strea ms. Some species, such as S. medusaeforme, inhabit a wide range of water-qu ality conditions, but at least five species are restricted to excellent-qua lity water, and three species were typically found in polluted water. Tempo ral changes in blackfly distribution and abundance are related to longterm drought/flood cycles, as well as increased river regulation and catchment d evelopment. The mammalophilic S. damnosum s.l. is recorded for the first ti me from the southwestern Cape, and S. lumbwanum de Meillon, a species whose larvae and pupae are phoretic on certain mayfly nymphs, is recorded for th e first time from South Africa and Swaziland.