Key to genera of Neotropical Microdontinae mimicking stingless bees

1. Hind tibia without long pile and not conspicuously widened............................ other groups of Microdontinae

– Hind tibia appearing corbiculate (as in bees): with long, brush-like pile and / or hind tibia conspicuously widened medially or apically............................................................................................. 2

2. Scutellum with calcars......................................................... other groups of Microdontinae

– Scutellum without calcars............................................................................... 3

3. Sternites 2 and 3 separated by unusually wide membraneous parts, about as wide as tergite 2 medially or wider (fig. 152, 153) (may be hard to see in dry specimens). Aedeagus unfurcate (figs. 230–251)............................... Stipomorpha

– Sternites 2 and 3 not separated by very wide membraneous part. Aedeagus furcate apically or basally (figs. 55–57, 108–112, 124–126, 265–266)..................................................................................... 4

4. Vein R4+5 with posterior appendix in cell r4+5 (e.g. figs. 40, 161, 165)........................................... 5

– Vein R4+5 without posterior appendix in cell r4+5 (e.g. figs. 8, 62, 87)........................................... 7

5. Tergites 3 and 4 not fused, posterior margin of tergite 3 strongly overlapping with tergite 4 (figs. 31, 37). Tergite 4 in lateral view perpendicular to tergite 2. Face in most species laterally depressed, appearing somewhat carinate medially........ Ceratophya