Abai, MR

6th International Congress of DipterologyWhy Hilara is not amusing, or the problem of speciosecosmopolitan generaBickel, D.J.Australian Museum, 6 College Street, Sydney, NSW 2010 Australiadan.bickel@austmus.gov.auMale Hilarini (Family Empididae) often have enlarged fore basitarsus,known to produce silk for wrapping prey or debris to present as nuptialgifts. Hilara and related genera are frequently seen cruising back andforth (happy, cheerful little flies) over pools along streams, hence thecommon name, “dance flies”. The genus is best known in Europe wheresome 174 species have been described. However, Hilara is cosmopolitanand conservatively comprises several thousand species, mostlyundescribed/ uncollected. This is complicated by Hilara s.l. having asimilar facies and suite character expression throughout the world.Further, Hilara and the related southern temperate Hilarempis areseparated by a venation character can be variable among species.Since many diagnostic characters are variable in expression, supraspecifictaxa have to be defined as a mosaic of characters, a "polytheticclassification," no character necessarily being diagnostic for all members.Although small, often regional genera/ species groups based onsynapomorphies can be defined, one is left with a large paraphyleticresidue of species that can only be lumped into large ill-defined genera.Paraphyly is a fact of taxonomic life.Examples of “open-ended speciose” cosmopolitan taxa from other familiesare discussed. G.G. Simpson’s “bradytelic” evolution in a stable adaptivezone provides a model. Speciation with a limited suite of morphologicalcharacters can result in many species accumulating over time, withhomoplasy throughout.With a conservative estimate of 10 million morphospecies, and some 1.7million already described (esp. larger, prominent species), then most of the23