Empis

Abstract: The Empis (Enoplempis) mira species group is revised and includes the type species of Enoplempis and four new species (E. macdonaldi sp. nov., E. submira sp. nov., E. williamturneri sp. nov., E. winkleri sp. nov.). A lectotype is designated for Enoplempis mira Bigot. The species group is defined by the yellow body colour, directionally asymmetrical male hindlegs and geniculate hindlegs in both males and females. The group has not been found outside of western North America and is known from California, Oregon, Idaho and Washington.

Abstract: The Empididae fauna of Serbia is summarised including currently 50 confirmed species belonging to nine genera: Clinocerinae-Kowarzia Mik (1), Phaeobalia Mik (2), Wiedemannia Zetterstedt (4); Empidinae-Empis Linnaeus (16), Hilara Meigen (11), Rhamphomyia Meigen (6); Hemerodromiinae-Chelifera Macquart (7), Hemerodromia Meigen (2), Phyllodromia Zetterstedt (1). A checklist of species is provided. Empis (Empis) serbica sp. nov. is described.

Abstract: The courtship and mating behaviour of three empidid flies Empis trigramma , E. tessellata and E. opaca are described. In E. trigramma the male appears to use his complex genitalia to introduce a liquid ‘gift’ into the female's abdomen during copulation. This ‘gift’ is subsequently discharged and imbibed by the female. Such male ‘gifts’ may constitute a direct investment in their offspring, as females do not seem to acquire significant nutritional input from other sources. Males of E. opaca and E. tessellata present a ‘gift’ to the female, in the form of a dead insect, before mating takes place. Females will not mate with males which do not present a gift. Gifts presented during the period of sexual activity also appear to make a substantial contribution to female ovarian development. Some males seek to ‘cheat’ by presenting substitute gifts in the form of the fluff-bearing seeds of willows. In E. opaca such ‘cheats’ enjoyed a low rate of reproductive success, compared with males presenting food gifts. ‘Cheating’ appears to be an alternative mating tactic for males of this species.

Abstract: A new dance fly (Empididae: Empidinae) with hugely modified male fore tarsus, either on the right, left, both or neither sides, is described from Japan. Such massive polymorphic asymmetry occurring with so high an incidence in a population is previously unreported. In view of the courtship behaviour of other Empidinae, we hypothesize that the oversized tarsus is a secondary sexual character employed by males for attracting females. Alternative hypotheses are also discussed. We suggest that this extraordinary new species is a potential model for the study of mating biology in Empidinae and the evolution of mating systems in general.