Key to species of Omalium of China

1 Temples elongate, with subacute angles distinctly protruded basad.............................................. 2

- Temples short or elongate, without subacute angles.......................................................... 4

2 Anterior angles of pronotum acute. Median lobe with broadened preapical and apical portions (Fig. 10). Habitus as in Fig. 3. Body length: 3.54 mm. Yunnan ...................................................................... sectum

- Anterior angles of pronotum rounded. Median lobe different................................................... 3

3 Antennomere 8 distinctly transverse. Pronotum moderately narrow, widest in middle; dorsal impressions relatively shallow. Median lobe short and wide, concave in preapical portion, with widely rounded apex; parameres narrow (Fig. 4); lateral portion of median lobe (laterally) as in Fig. 6. Female accessory sclerite as in Fig. 13. Habitus as in Fig. 1. Body length: 2.45–3.35 mm. Sichuan, Shaanxi ............................................................................ anguliferum

- Antennomere 8 narrow. Pronotum distinctly transverse, widest in anterior third; dorsal impressions deep. Median lobe elongate, from broadest middle gradually narrowed toward relatively small rounded apex; parameres wide (Fig. 7); lateral portion of median lobe (laterally) as in Fig. 9. Female accessory sclerite as in Fig. 14. Habitus as in Fig. 2. Body length: 2.57–3.10 mm. Shaanxi, Yunnan ................................................................................. rutilum

4 Anteocellar fovea narrow and linear. Aedeagus as in Fig. 34; lateral portion of median lobe (laterally) as in Fig. 36. Body dark-brown, with paler elytra. Habitus as in Fig. 31. Body length: 2.80 mm. Shaanxi .............................. pratense

- Anteocellar foveae wide and deep, short, suboval or long, usually convergent latero-anteriad. Coloration of body different.. 5

5 Pronotum widest in anterior third......................................................................... 6

- Pronotum widest in or in about middle................................................................... 11

6 Temples short, more than three times as long as longitudinal length of eyes. Pronotum with deep medioapical depression and strongly elevated middle portions around pronotal depressions.Aedeagus as in Fig. 79; lateral portion of median lobe (laterally) as in Fig. 81. Female accessory sclerite as in Fig. 27. Habitus as in Fig. 76. Body length: 2.93–3.95 mm. Zhejiang, Hubei, Shaanxi, Sichuan ............................................................................. rougemonti

- Temples distinctly longer. Pronotum without or with relatively shallow medioapical depression; middle portions slightly elevated around pronotal depressions...................................................................... 7

7 Anteocellar foveae suboval, indistinctly convergent latero-apicad. Temples about twice as long as longitudinal length of eyes. Median lobe significantly broadened, spoon-shaped, with widely rounded apex; parameres relatively narrow (Fig. 40); lateral portion of median lobe (laterally) as in Fig. 43. Female accessory sclerite as in Fig. 16. Habitus as in Fig. 32. Body length: 2.70–3.56 mm. Yunnan, Sichuan ................................................................... cocleare

- Anteocellar foveae elongate and moderately long, distinctly convergent latero-apicad. Temples distinctly less than twice as long as eyes. Median lobe narrow and elongate, parameres broader.................................................. 8

8 Head, pronotum and abdomen reddish-brown; elytra brown to reddish-brown. Aedeagus as in Fig. 69; lateral portion of median lobe (laterally) as in Fig. 71. Female accessory sclerite as in Fig. 26. Habitus as in Fig. 64. Body length: 2.70–3.75 mm. Qinghai, Sichuan .................................................................................. lama

- Body brown to reddish-brown........................................................................... 9

9 Median lobe wide; parameres short (Fig. 37 and Fig. 43 in Shavrin 2023a); lateral portion of median lobe (laterally) as in Fig. 45 in Shavrin (2023a). Female accessory sclerite as in Fig. 13 in Shavrin (2023a). Habitus as in Fig. 40–41 in Shavrin (2023a). Body length: 1.72–2.80 mm. India, Nepal, China ....................................................... alticola

- Median lobe narrow; parameres long..................................................................... 10

10 Median lobe broadened in preapical portion; parameres narrow, reaching middle length of median lobe (Fig. 44); lateral portion of median lobe (laterally) as in Fig. 46. Female accessory sclerite as in Fig. 18. Habitus as in Fig. 33. Body length: 2.42–3.70 mm. Yunnan, Sichuan ............................................................................ contiger

- Median lobe broadened in middle; parameres distinctly broadened in middle portions, reaching preapical part of median lobe (Fig. 85); lateral portion of median lobe (laterally) as in Fig. 87. Habitus as in Fig. 78. Body length: 2.87–3.20 mm. Yunnan .............................................................................................. tibetanum

11 Anteocellar foveae significantly broadened, strongly convergent latero-apicad and connected with latero-apical depressions. Aedeagus as in Fig. 66; lateral portion of median lobe (laterally) as in Fig. 68. Female accessory sclerite as in Fig. 24. Body dark-brown. Habitus as in Fig. 63. Body length: 2.90–2.95 mm. Sichuan .................................. confertum

- Anteocellar foveae moderately broad, not or slightly convergent latero-apicad.................................... 12

12 Elytra yellow-brown.................................................................................. 13

- Elytra distinctly darker, brown to reddish-brown or black..................................................... 14

13 Pronotum from widest middle gradually narrowed both posteriad and anteriad. Punctation of pronotum distinclty sparser. Median lobe with widely rounded projections in middle; apical parts of parameres narrow (Fig. 72); lateral portion of median lobe (laterally) as in Fig. 74. Habitus as in Fig. 65. Body length: 3.30–3.35 mm. Gansu ................. pseudojaponicum

- Pronotum from widest middle distinctly more narrowed posteriad than anteriad. Punctation of pronotum moderately dense. Median lobe without median projections; apical parts of parameres significantly broadened (Fig. 59); lateral portion of median lobe (laterally) as in Fig. 61. Female accessory sclerite as in Fig. 22. Habitus as in Fig. 52. Body length: 2.45–3.10 mm. Jiangxi ................................................................................. bambusaphilum

14 Anterior angles of pronotum slightly protruded anteriad...................................................... 15

- Anterior angles of pronotum not protruded anteriad......................................................... 16

15 Median lobe moderately broadened, with widely rounded apex; apical portions of parameres moderately narrow (Fig. 53); lateral portion of median lobe (laterally) as in Fig. 55. Female accessory sclerite as in Fig. 20. Body reddish-brown. Habitus as in Fig. 50. Body larger: 3.47–4.35 mm. Anhui ........................................................ kurbatovi

- Median lobe moderately narrow, from widest preapical portion gradually narrowed toward small rounded apex; apical portions of parameres distinctly broadened (Fig. 1b in Zheng & Pu (2000)). Body black, with dark-brown elytra. Habitus as in Fig 1a in Zheng & Pu (2000). Body smaller: 3.10 mm. Xizang ................................................. xizangense

16 Median lobe narrow; parameres wide (Fig. 82); lateral portion of median lobe (laterally) as in Fig. 84. Female accessory sclerite as in Fig. 29. Body dark-brown, with slightly paler elytra. Habitus as in Fig. 77. Body length: 2.40–2.86 mm. Yunnan ................................................................................................... smetanai

- Median lobe wide; parameres narrow.................................................................... 17

17 Anteocellar foveae short. Aedeagus as in Fig. 46 in Zanetti (1987). Female accessory sclerite as in Fig. 48o in Zanetti (1987). Body brown to black. Body length: 2.20–2.60 mm. Holarctic region.................................... oxyacanthae

- Anteocellar foveae elongate, slightly convergent latero-apicad toward level of posrerior third or middle length of eyes.Aedeagus as in Fig. 56; lateral portion of median lobe (laterally) as in Fig. 58. Body reddish-brown. Habitus as in Fig. 51. Body length: 2.65–3.50. Gansu, Sichuan ........................................................................ schuelkei