Key to species of Microdacne

1. Pronotum with distinct sublateral sulcus on basal 2/3 of pronotal length (Fig. 29); Mt. Glorious, Queensland ..................................................................................... Microdacne gloriousa, new species

- Pronotum with sublateral sulcus greatly reduced or absent..................................................... 2

2(1). Pronotal sublateral sulcus short, distinct only at posterior angle (Fig. 28); Styx River, near Wollomombi, New South Wales ............................................................................ Microdacne styxia, new species

- Pronotal sublateral sulcus lacking at posterior angle, remnant visible at middle of pronotum.......................... 3

3(2). Pronotal sublateral sulcus vague but present medially, near lateral margin (Fig. 25); tibia black with pale base; Mt. Nardi, Night- cap National Park, New South Wales ............................................ Microdacne nardia, new species

- Pronotal sublateral sulcus reduced to series of large punctures near lateral margin (Fig. 20); tibia entirely black; Lamington National Park, Queensland ................................................ Microdacne lamingtonia, new species