A contribution to a generic revision of the neotropical Milesinae (Diptera: Syrphidae)

Abstract

A revised generic classification of the Neotropical Milesinae is proposed. Twelve tribes, six subtribes and forty-two genera are recognized and keys to these taxa are provided. Detailed descriptions of the tribes and genera, along with a discussion of the new characters used; are included. The male genitalia and some of the other principal characters for almost all the genera are figured. One new genus (Notiocheilosia, type-species Chilosia nitescens Shannon and Aubertin) is described. The following new synonymies are made: Copestylum Macquart (= Apophysophora Williston, =Megametopon Giglio-Tos, Viereckomyia Currran, =Lepidopsis Curran, =Volosyrpha Shannon and = Volucellosia Curran); Dolichogyna Macquart (=Nosodepus Speiser); Habromyia Williston (=Edwardsietta Hull, = Lycopale Hull and = Criorthrix Hull); Meromacrus Rondani (= Thalamopales Hull); and Sterphus Philippi (=Crepidomyia Shannon, =Tatuomyia Shannon, =Senoceria Hull and =Mutillimyia Hull). Copestylum Macquart is recognised for the New World species of Volucella Geoffroy. Chromocheilosia Hull and Fluke is given full genewic status and transferred from Cheilosia (Cheilosini) to the tribe Chrysogasterini. Eristalis Latreille is partitioned into Eristalis, s.s., Eoseristalis Kanervo and Palpada Macquart. Zoogeography of the Neotropical milesine fauna is discussed. The gross statistics of the fauna are compared to those of other regions and these statistics indicate a long-isolated fauna. The distributional patterns and phylogenetic relationships of the Neotropical genera are also analyzed and these patterns and relationships support a Nearctic origin for almost all of the South American milesine flies. Continental Drift and its possible effect on the Neotropical fauna is also briefly reviewed. Finally the transition between the Nearctic and Neotropical milesine faunas is examined and this transition appears to consist of predominantly Neotropical groups that have moved northward, whereas only one Nearctic group has moved southward in the transitional zone.