Key to the species of Marbenia Malloch

1. Frons brown or pale brown with lateral margins yellow; face brown with small yellow spots (Fig. 17); wing predominantly brown, with basal 1/3 yellowish and 2 hyaline spots in the brownish portion (Fig. 19)......... Marbenia peculiaris Malloch

- Frons entirely yellow; face pale brown or yellow (Figs 2, 9); wing yellowish tinged with apical, posterior margin and a transverse band gray (Figs 4, 11)............................................................................. 2

2. Scutum covered with sparse pale gray pruinescence (Fig. 3); face pale brown, lacking spots, with 1 transversal furrow (Fig. 2); gena and postgena brown; abdomen brown............................................ Marbenia cinerea, sp. nov.

- Scutum covered by dense golden pruinescence (Fig. 10); face yellow with lateral margins darkened on upper half, with 2 deep transversal furrows (Fig. 9); gena and postgena yellow; abdomen pale brown................. Marbenia pallida, sp. nov.