Key to the Australian species of Sirthenea

1 Scape short, reaching apex of head; legs dark brown; mid tibia without fossula spongiosa; eyes not reaching dorsal and ventral outlines of head in lateral view (Fig. 144)....................................... S. (Sirthenea) obscura (Stål, 1866)

- Scape long, surpassing apex of head; legs yellowish; mid tibia with fossula spongiosa; eyes reaching dorsal and ventral outlines of head in lateral view (Figs. 131, 132, 159–163)........................ S. (Monogmus) laevicollis Horváth, 1909