Key to males and females of the European species of Hebecnema Schnabl

1 All femora mainly dark. Vein C bare dorsally............................................................... 2

- Mid and hind femora yellow. Vein C with setulae dorsally distal to middle........................ H. nigricolor (Fallén)

2 Head narrow fronted: males............................................................................ 3

- Head broad fronted: females............................................................................ 8

3 Eye with distinct pile.................................................................................. 4

- Eye practically bare................................................................................... 5

4 Parafacials in anterodorsal view silvery white pruinose. Head in profile with parafacial visible throughout. Abdomen with narrow median dark stripe at the least well visible on tergites III(‒IV). Legs wholly dark............. H. umbratica (Meigen)

- Parafacials in anterodorsal view dull brown pruinose. Head in profile with parafacial concealed on middle part. Abdomen without a median dark stripe. Legs dark with ochre yellow tibiae................................... H. fumosa (Meigen)

5 Halter at the least blackish on distal half................................................................... 6

- Halter wholly yellow................................................................. H. vespertina (Fallén)

6 Parafacials in anterodorsal view dull brown pruinose. Head in profile with parafacial concealed on middle part. Calypteres of same dark colour as wing base.......................................................................... 7

- Parafacials in anterodorsal view silvery white pruinose. Head in profile with parafacial fully visible. Calypteres dirty whitish, paler than light brown wing base.................................................. H. nigra (Robineau-Desvoidy)

7 Sternite V and hypopygium as in Figs 1 A‒C. Madeira ......................................... H. anthracina Stein

- Sternite V and hypopygium as in Figs 2 A‒C. Canary Islands .............................. H. anthracinella sp. nov.

8 Halter wholly yellow.................................................................................. 9

- Halter at the least blackish on distal half.................................................................. 11

9 Abdomen with greyish pruinosity delimiting a median dark stripe............................................. 10

- Abdomen uniformly shiny black through thin brownish pruinosity............................. H. vespertina (Fallén)

10 Parafacials in anterodorsal view whitish grey pruinose. Legs wholly dark........................ H. umbratica (Meigen)

- Parafacials in anterodorsal view dull brownish pruinose. Legs dark with tibiae ochre brown to ochre yellow.................................................................................................. H. fumosa (Meigen)

11 Parafacials in anterodorsal view dull brownish pruinose. Presutural rows of fine acrostichal setae distinctly wider apart than their distance to adjacent rows of dorsocentral setae. Calypteres of same dark colour as wing base.................... 12

- Parafacials in anterodorsal view silvery white pruinose. Presutural rows of relatively strong acrostichal setae about as far apart than their distance to adjacent rows of dorsocentral setae. Calypteres dirty whitish, paler than light brown wing base................................................................................... H. nigra (Robineau-Desvoidy)

12 Endemic to Madeira ................................................................. H. anthracina (Stein)

- Endemic to the western Canary Islands ................................................ H. anthracinella sp. nov.