Key to species of Hypselosyrphus

1. Scutellum triangular, apex acute. (fig. 65)......................................................... amazonicus

– Scutellum not triangular: semicircular or apicomedially sulcate.................................................. 2

2. Alula entirely microtrichose............................................................................. 6

– Alula with small bare area basomedially................................................................... 3

3. Thorax and abdomen entirely yellow (fig. 70, 71)........................................................ helvus

– Thorax and abdomen largely black........................................................................ 4

4. Basoflagellomere about as long as scape or longer. Wing either with strongly contrasting yellowish patch posteriad of pterostigma (male) or with middle 1/3 strongly contrasting whitish yellow (female) (figs. 74, 75)................ marshalli

– Basoflagellomere maximally half as long as scape. Wing without strongly contrasting yellow parts..................... 5

5. Tergite 4 with posterior margin widely yellowish; sternite 4 largely yellowish. Scutellum entirely black pilose. Wing tinged yellowish on apical third, otherwise brownish............................................................. anax

– Tergite and sternite 4 entirely blackish brown. Scutellum black pilose, except pale pilose posteroventrally. Wing entirely tinged brownish..................................................................................... plaumanni

6. Wing with contrasting pattern of dark brown and yellow fasciae (fig. 87, 106)...................................... 7

– Wing without contrasting colour pattern (may be tinged with brown or yellow)..................................... 8

7. Mesonotum and scutellum yellow pilose............................................................... pingo

– Mesonotum and scutellum black pilose........................................................... vexillipennis

8. Hind tibia yellow, yellow pilose. Only female known................................................ corbiculipes

– Hind tibia at least partly brown, black pilose................................................................ 9

9. Abdomen orange to reddish brown...................................................................... 11

– Abdomen black...................................................................................... 10

10. Occiput narrow over entire length (fig. 79)............................................................. maurus

– Occiput ventrally widened (fig. 103)................................................................ ulopodus

11. Scutellum apicomedially sulcate. Face dark brown. Thorax dark brown..................................... trigonus

– Scutellum more or less semicircular, not sulcate. Face yellow. Thorax yellow, except for blackish brown maculae on mesoscu- tum....................................................................................... pseudorhoga