Acerocnema, Becker, 1894

Chagnon, Marie-Eve & Sinclair, Bradley J., 2021, Revision of Nearctic species of Acerocnema Becker (Diptera: Scathophagidae), Zootaxa 4952 (3), pp. 523-539 : 525

Key to Nearctic species of Acerocnema

1 Yellow; abdomen in both sexes with brownish fascia at posterior margin of each tergite ( Figs 17 , 21 )................................................................................................. Acerocnema rufula (Curran)

- Black or dark brown; male abdomen black or dark brown ( Figs 15–18 ); female abdomen dark brown or yellowish with black fascia medially ( Figs 19, 21, 22 )......................................................................... 2

2 Vein R 1 with several apical dorsal setulae; male abdomen black to pale brown ( Fig. 15 ); female abdomen with black fascia medially ( Fig. 19 )......................................................... Acerocnema fasciventris (Malloch)

- Vein R 1 without apical dorsal setulae; male and female abdomen black, rarely with black fascia medially ( Figs 20, 22 )..... 3

3 Scutum with 3 dorsocentrals; male postpedicel yellow ( Fig. 16 ); female postpedicel sometimes spotted black, at least base yellow ( Fig. 20 ); scutum with pair of shiny vittae on posterior half........................... Acerocnema merga sp. nov.

- Scutum with 5 dorsocentrals; postpedicel completely black in both sexes ( Figs 15 , 19 ); scutum without shiny vittae..................................................................................... Acerocnema vanga sp. nov.

Figures

FIGURES 15–18. Acerocnema male species, habitus lateral views. 15. A. fasciventris (Malloch); 16. A. merga sp. nov.; 17. A. rufula (Curran); 18. A. vanga sp. nov.

FIGURES 19–22. Acerocnema female species, habitus lateral views. 19. A. fasciventris (Malloch); 20. A. merga sp. nov.; 21. A. rufula (Curran); 22. A. vanga sp. nov.