Abai, MR

6th International Congress of DipterologyMoegistorhynchus Macquart, a remarkable endemic genusof Nemestrinidae and important pollinator of long-tubedflower species along the west coast of South AfricaBarraclough D. A.School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban4041, South Africa; barracloughd@ukzn.ac.zaAbout 80% of Afrotropical Nemestrinidae species are restricted to SouthAfrica, where Prosoeca, Moegistorhynchus and Stenobasipteron dominatethe fauna. Interest in these genera has increased over the last two decades,because each includes long-proboscid species importance in pollinationbiology. Moegistorhynchus is South Africa’s only endemic nemestrinidgenus, and is restricted to the west coast. It is immediately recognized byits reticulate wing venation and patterned wings. Most species are large,robust flies, 1.5–2.0 cm in length. Proboscis length varies from ca 1–10 cm.Plant species pollinated have an unusually elongate floral tube and offernectar rewards.Of the six species in the genus, Moegistorhynchus longirostris is by far themost abundant. It has the longest proboscis known in the Diptera (ca 3–10cm) and is widely distributed across much of the genus’s range, but at lowaltitude. M. perplexus (proboscis length ca 3–5 cm) occurs at higheraltitude and has a much more restricted range. M. brevirostris and M.braunsi have limited ranges in the extreme south, both at low altitude. M.brevirostris has the shortest proboscis in the genus (less than 2 cm) and isprobably of no significance as a pollinator. Two new species are recordedfrom southern montane localities; one has a proboscis length of 2 cm andappears to be the unique pollinator of a Gladiolus species.Twenty species of Iridaceae, Geraniaceae and Orchidaceae are pollinatedpartly or exclusively by M. longirostris, which is a keystone species. Theincredible variation in proboscis length of this species shows a markedtrend of longer forms in the north, ranging to shorter forms in the south,16