| 1 | Bright, orange-coloured species. Scape and pedicellus yellow. | 2 |
| – | Unicolorous, brownish species. Scape and pedicellus not brightened. | 3 |
| 2 | Body nearly unicolored, orange. CuA2 and stM with macrotrichia. Tibial comb on fore tibia divided. | Ctenosciara lutea (Meigen, 1804) |
| – | Body bicolored, thorax mainly orange, abdomen mainly brown. CuA2 and stM without macrotrichia. Tibial comb on fore tibia undivided. | Ctenosciara alexanderkoenigi sp. n. |
| 3 | Larger species, wing length > 2 mm. CuA2 with more than 10 macrotrichia. Front tibial comb strictly divided. Tegmen conical, longer than broad. | Ctenosciara hyalipennis (Meigen, 1804) |
| – | Smaller species, wing length ≤ 2 mm. CuA2 bare or with less than 8 macrotrichia. Apical comb on fore tibia undivided or unclearly divided. Tegmen roundish, not longer than broad. | Ctenosciara exigua Salmela & Vilkamaa, 2005 |
All currently known European species of Ctenosciara (Fig. 5) share the following characters:
Posterior wing veins (at least M1, M2, stM and CuA1) with macrotrichia
Apical part of fore tibia with a bordered tibial comb, which is mostly divided
Gonostylus simple, elongate, with apical tooth and a group of subapical megasetae.