| 1 | | | |
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| 2 | | | |
| – | | | Rs absent or discernible only as a non-sclerotized fold | ► 3 |
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| 3 | | | Proboscis short, at most two and a half times the height of head | ► 4 |
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| – | | | Proboscis long, four or more times as long as the height of head | ► 5 |
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| 4 | | | Subcosta ending in costa, costa R1 meeting at the middle of wing | | | Asiorrhina Blagoderov et alia |
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| – | | | Sc ending free, R1 meeting costa well within the basal half of wing | | | Labellorrhina Hippa et alia |
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| 5 | | | Middle tibia with two apical spurs | | | Lygistorrhina Skuse, subg. Lygistorrhina |
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| – | | | Middle tibia with one apical spur | | | Lygistorrhina Skuse, subg. Probolaeus |
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| 6 | | | Hind basitarsomere swollen, as broad as apical part of hind tibia | ► 7 |
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| – | | | Hind basitarsomere thin, narrower than apical part of hind tibia | ► 9 |
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| 7 | | | C with a swelling at the apex of vein R1, proboscis very short, about one-tenth the height of head | | | Seguyola Matile |
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| – | | | C without a swelling at the apex of R1, proboscis long, as long as or longer than the height of head | ► 8 |
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| 8 | | | Number of antennal flagellomeres 12, R1 meeting the costal margin well in basal half of wing | | | Loyugesa Grimaldi & Blagoderov |
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| – | | | Number of antennal flagellomeres 14, R1 meeting the costal margin at the middle of wing | | | Matileola Papp |
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| 9 | | | Number of antennal flagellomeres 14, the flagellomeres ventrally greatly expanded, proboscis one-half the height of head,CuA1 and CuA2 with a long common stem (stCuA) | | | Gracillorrhina Hippa et alia |
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| – | | | Number of antennal flagellomeres 12, the flagellomeres normal, not ventrally expanded, proboscis longer than the height of head, CuA1 and CuA2 separate | | | Blagorrhina Hippa et alia |
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