3.3. Key to species of Omalium of Siberia, Far Eastern Russia, Mongolia and Japan

1 Anteocellar foveae narrow, linear......................................................................... 2

- Anteocellar foveae deep, suboval and relatively short or distinctly elongate....................................... 3

2 Lateral portions of pronotum significantly broadened and impressed, strongly narrowed posteriad. Elytra shortened, broader than long. Median lobe relatively narrow (Fig. 6). Female accessory sclerite as in Fig. 14. Body length: 2.72–3.45 mm. Habitus as in Fig. 2. Western Siberia ...................................................................... golovatchi

- Lateral portions of pronotum narrowly impressed, slightly narrowed posteriad. Elytra elongate, distinctly longer than broad. Median lobe distinctly broadened in middle (Fig. 11 in Shavrin & Khachikov (2023)). Female acessory sclerite as in Fig. 48u in Zanetti (1987). Body length: 2.50–3.50 mm. Habitus as in Fig. 1 in Shavrin & Khachikov (2023). Palaearctic region................................................................................................... caesum

3 Lateroapical portions of pronotum strongly protruded anteriad. Aedeagus as in Fig. 1 in Smetana (1975). Body length: 2.50– 2.80 mm. Habitus as in Fig. 41. Mongolia ............................................................ scabrum

- Lateroapical portions of pronotum not or slightly protruded anteriad............................................. 4

4 Elytra yellow-brown................................................................................... 5

- Elytra distinctly darker................................................................................. 8

5 Pronotum relatively small, slightly transverse. Median lobe short and broad; parameres strongly elongate (Fig. 64 in Watanabe (1990)). Body smaller: 2.10–2.20 mm. Japan ............................................................ tenue

- Pronotum larger, distinctly transverse. Median lobe long and narrow; parameres distinctly shorter. Body larger........... 6

6 Apical angles of pronotum slightly narrowed anteriad. Lateroapical part of median lobe (if see laterally) with several elongate teeth (Fig. 29). Female accessory sclerite as in Fig. 16. Body length: 3.25–4.00 mm. Habitus as in Fig. 34. Kuril islands................................................................................................. kurilicum

- Apical angles of pronotum widely rounded anteriad. Lateroapical part of median lobe different........................ 7

7 Elytra slightly broader than long. Aedeagus as in Fig. 38–39. Body length: 3.17–3.70 mm. Habitus as in Fig. 35. Russia (Maritime Province), Japan ...................................................................... niponense

- Elytra slightly longer than broad. Body length: 3.70–4.10 mm. Japan ....................................... shibatai

8 Antennomeres 6–10 distinctly elongate.Aedeagus as in Fig. 4. Body length: 3.06–4.10 mm. Female accessory sclerite as in Fig. 17. Body yellow-brown to reddish-brown. Habitus as in Fig. 1. Eastern Siberia, Far Eastern Russia, Mongolia ... longicorne

- Antennomeres 6–10 slightly or distinctly transverse. Coloration different......................................... 9

9 Body brown to reddish-brown, usually with paler elytra...................................................... 10

- Body usually darker, including elytra..................................................................... 14

10 Pronotum slightly transverse, with dense punctation......................................................... 11

- Pronotum distinctly transverse, with moderately sparse punctation............................................. 13

11 Pronotum somewhat elongate, from widest middle gradually narrowed anteriad and posteriad. Median lobe narrow and elongate; lateroapical part of median lobe relatively wide (if see laterally), forming large preapical tooth (Fig. 36)... Female accessory sclerite as in Fig. 15. Body length: 2.15–3.20 mm. Habitus as in Fig. 33. Japan, Korea,? China ................. japonicum

- Pronotum distinctly transverse, from widest middle or apical third more narrowed posteriad than anteriad. Median lobe different; lateroapical part of median lobe (if viewed laterally) without preapical tooth..................................... 12

12 Median lobe wide and elongate; parameres narrow (Fig. 46a in Zanetti 1987). Female accessory sclerite as in Fig. 48o in Zanetti (1987). Body length: 2.30–2.50 mm. Habitus as in Fig. 3. Holarctic region............................... oxyacanthae

- Median lobe narrow, moderately short; parameres wide (Figs 44, 46). Female accessory sclerite as in Fig. 19. Body length: 1.90–2.60 mm. Habitus as in Fig. 43. Siberia, Far Eastern Russia, Japan .................................. subsolanum

13 Laterobasal portions of pronotum slightly narrowed posteriad. Median lobe moderately short, with distinctly broadened preapical portion (Fig. 45c in Zanetti (1987)). Female accessory sclerite as in Fig. 48e in Zanetti (1987). Body length: 3.50–4.00 mm. Holarctic region............................................................................. rivulare

- Laterobasal portions of pronotum more distinctly narrowed posteriad. Median lobe elongate, with slightly broadened preapical portion (Figs 25, 27). Female accessory sclerite as in Fig. 10. Body length: 2.25–3.70 mm. Habitus as in Fig. 23. Norway, Siberia, Far Eastern Russia ....................................................................... curtipenne

14 Body smaller: 2.20–2.38 mm. Aedeagus as in Fig. 8. Female accessory sclerite as in Fig. 12. Body brownish. Habitus as Fig. 24. Japan ........................................................................................ diffine

- Body about or distinctly more than 3.00 mm. Coloration darker................................................ 15

15 Pronotum slightly broader than long. Median lobe from widest middle strongly narrowed toward acute apex; lateroapical part of median lobe narrow (if see laterally), not forming preapical tooth (Figs. 9–10 in Hayashi (2006)). Body length: 2.70–3.50 mm. Body dark brown to blackish brown. Habitus as in Fig. 1 in Hayashi (2006). Japan ...................... hibernum

- Pronotum more transverse, distinctly broader than long. Median lobe different; lateroapical part of median lobe relatively wide (if see laterally), forming preapical tooth.................................................................. 16

16 Pronotum from widest middle gradually narrowed both anteriad and posteriad. Maxillary palpi yellow to yellow-brown. Median lobe significantly broadened; parameres short and narrow (Fig. 53f in Zanetti (2011). Body length: 3.00– 3.50 mm. Body brown to reddish-brown. Habitus as in Fig. 22. Palaearctic region............................................ septentrionis

- Pronotum from widest middle or preapical third more narrowed posteriad than anteriad. Maxillary palpi distinctly darker. Median lobe narrow; parameres wide and relatively long (Fig. 49). Body length: 2.40–3.10 mm. Body reddish-brown. Habitus as in Fig. 42. Holarctic region.................................................................... strigicolle