Key to species of Anthobium nigrum group (modified Shavrin & Smetana 2017)

1 Lateral edges of pronotum with very indistinct smooth crenulation, latero-apical margins of elytra with moderately large teeth. Head reddish-brown, pronotum, elytra and abdomen yellow-brown. Aedeagus as in Fig. 98. Habitus as in Fig. 95. Body length: 3.15–3.64 mm. Nepal ................................................... A. flaveolum Shavrin & Smetana, sp.n.

- Lateral edges of pronotum with distinct crenulation, latero-apical margins of elytra with small acute teeth. Body darker..... 2

2 Anterior angles of pronotum strongly protruded anteriad. Elytra markedly wider than long. Aedeagus as in Fig. 77 (Shavrin & Smetana 2017). Habitus as in Fig. 67 (Shavrin & Smetana 2017). Body length: 3.90–4.20 mm. China: Yunnan ................................................................................. A. conjunctum Shavrin & Smetana, 2017

- Anterior angles of pronotum slightly protruded anteriad. Elytra as wide as long or slightly longer than wide.............. 3

3 Punctation of pronotum very dense. Aedeagus as in Fig. 80 (Shavrin & Smetana 2017). Habitus as in Fig. 68 (Shavrin & Smetana 2017). Body length: 3.50–4.27 mm. China: Yunnan ............... A. densepunctatum Shavrin & Smetana, 2017

- Punctation of pronotum sparse.......................................................................... 4

4 Pronotum slightly flattened in cross section, with indistinct mediobasal impression. Aedeagus as in Fig. 72 (Shavrin & Smetana 2017). Habitus as in Fig. 66 (Shavrin & Smetana 2017). Body length: 4.15–4.37 mm. China: Gansu .................................................................................A. anishchenkoi Shavrin & Smetana, 2017

- Pronotum very convex, with deep mediobasal impression...................................................... 5

5 Middle portion of head distinctly convex, with indistinct transverse impression. Aedeagus as in Fig. 70 (Shavrin & Smetana 2017). Habitus as in Fig. 65 (Shavrin & Smetana 2017). Body length: 3.44–4.75 mm. India ..... A. nigrum (Cameron, 1924)

- Middle portion of head flattened, without or with very indistinct transverse impression. Aedeagus different.............. 6

6 Elytra as wide as long. Body reddish-brown to black. Median lobe of aedeagus narrow, apical portions of parameres widened (Shavrin & Smetana 2017: Fig. 82). Habitus as in Fig. 69 (Shavrin & Smetana 2017). Body larger: 4.00– 4.71 mm. Nepal, Bhutan ...................................................................... A. ivani Shavrin & Smetana, 2017

- Elytra slightly longer than wide. Body brown. Median lobe of aedeagus moderately wide, apical portions of parameres narrow (Fig. 96). Habitus as in Fig. 94. Body smaller: 3.50 mm. Nepal ............................ A. alticola (Coiffait, 1977)