Introduction

Rhopalosyrphus is small group of large brownish to gray wasp mimics found only in the New World tropic. All species are rare, only 100 specimens known. The genus contains only 4 species: One species ranges from USA (Arizona to Texas)to Argentina and others are more restricted in range. This paper presents a revision of the genus, with complete synonymies, descriptions, and distributional and biological data for all taxa.

Rhopalosyrphus belongs to the subfamily Microdontinae and may be the sister to Microdon [Microdontinae = Paragodon + (Mixogaster + (Rhapolsyrphus + Microdon)), see Thompson & Whitehead (1986) for explanation of cladistic formulae] (Thompson et al. (in press)). The genus is defined (synapomorphy) by its antennal, facial and pleural structure andshort antenna, bare anepimeron, absence of spurious vein and spur in cell R wing venation.
Rhopalosyrphus is an endemic New World group consisting of 4 known species.