Key to species of Australian Megisthanidae (females required; males supplementary)

1. Dorsal shield lyriform (Fig. 6A); posterior dorsal shield setae thick, short, with strong barbs (Figs 7 D–E); internal genitalia with well-developed latigynal element (Fig. 7B)............................................................. 2

- Dorsal shield ovate (Fig. 1A); posterior dorsal setae slender, usually longer, smooth or with fine barbs (Figs 3D, 17C); internal genitalia lacking well-developed latigynal element (Figs 3 B–C)................................................. 3

2. Posterior dorsal shield setae each with 0–2 barbs (Fig. 7D)......................................... M. leviathanicus

- Posterior dorsal shield setae with many (ca. 10) barbs (Fig. 7E)................................. M. manonae sp. nov.

3. Seta pd2 on femur IV on large projection (Fig. 17D); dorsal shield densely covered with short fine setae (Fig. 16A); sternogynal shields widely separated (by about width of sternogynal shield) (Fig. 17A)................... M. womersleyi sp. nov.

- Seta pd2 on femur IV not on projection (Fig. 3E); dorsal shield less hypertrichous, with at least some long setae (Figs 1A, 12A, 21A); sternogynal shields not widely separated (by much less than width of sternogynal shield) (Fig. 3A)................ 4

4. Medial dorsal shield with two distinct types of setae: a short, heavily barbed form and a long, smooth or sparsely barbed form (Figs 11 A–B)......................................................................................... 5

- Medial dorsal shield with one type of seta, a long, smooth, barbed form (some long setae may be present on margins) (Figs 1A, 12A, 21A)........................................................................................... 6

5. Medial opisthosoma with distinct patch of short pilose setae (Fig. 11B)................................... M. thorelli

- Medial opisthosoma without distinct patch of short pilose setae (Fig. 11A), differentiation between long and short setal types less distinct than on podosoma........................................................... M. simoneae sp. nov.

6. Setae st4 present (Fig. 3A); host Pharochilus spp............................................. M. modestus sp. nov.

- Setae st4 absent (Figs 14A, 22B); host Aulacocyclus spp....................................................... 7

7. Podonotum and opisthonotum densely setose (Fig. 12A); genital setae long, 60–110; with 5–11 setae behind margin of genital shield (Fig. 14A); male sternoventral shield highly hypertrichous around genital opening (approximately 50-60 setae; Fig. 14D)............................................................................... M. southcotti sp. nov.

- Podonotum more setose than opisthonotum (Fig. 21A); genital setae short, 20–35; with 0–2 setae behind margin of genital shield (Fig. 22A); male sternoventral shield much less hypertrichous around genital opening (at most 20 setae; Fig. 22E)........................................................................................ M. zachariei sp. nov.