Amphichroum, Kraatz, 1857

Shavrin, Alexey V. & Smetana, Aleš, 2018, New species of the genus Amphichroum Kraatz, 1857 (Coleoptera: Staphylinidae: Omaliinae: Anthophagini) from China, Zootaxa 4508 (3), pp. 377-402 : 401-402

Key to species of Amphichroum of China

1 Basal portion of internal sac with paired, very large sclerotized structures......................................... 2

- Basal portion of internal sac with significantly smaller sclerotized structures or without them......................... 4

2 Pronotum with distinct longitudinal reddish-brown spot. Median lobe ( Fig. 14 ) markedly, evenly narrowed toward acute apex; internal sac with two very long apical thorns ( Fig. 15 ). Body length:2.00–2.35. Habitus as in Fig. 4 . Yunnan ................................................................................................... A. maculosum sp.n.

- Pronotum without spot. Shape of median lobe and internal sac different........................................... 3

3 Elytra longer than wide. Forebody yellow to yellow-brown, abdomen reddish-brown. Parameres slightly exceeding apex of median lobe; sclerotized structures in basal part of internal sac very large and wide ( Fig. 12 ). Body length:2.10–3.65. Habitus as in Fig. 3 . Sichuan .................................................................. A. longilobatum sp.n.

- Elytra distinctly wider than long. Body yellow-brown to reddish-brown. Parameres distinctly exceeding apex of median lobe; sclerotized structures in basal part of internal sac smaller and narrower ( Fig. 20 ). Body length:3.00–3.15. Habitus as in Fig. 16 . Sichuan ............................................................................. A. propinquum sp.n.

4 Apical portion of internal sac with wide thorns.............................................................. 5

- Apical portion of internal sac without wide thorns............................................................ 6

5 Aedeagus moderately wide, with short parameres ( Fig. 5 ); internal sac with two pairs of wide thorns in apical and complicated sclerotized structures in basal portion ( Fig. 5 ). Body length:2.85–3.10. Habitus as in Fig. 1 . Yunnan .. A. angustilobatum sp.n.

- Aedeagus narrow, with longer narrow parameres ( Fig. 24 ); internal sac with several wide thorns in apical and sclerotized ringlike structure in basal portion ( Fig. 25 ). Body length:2.20–3.75. Habitus as in Fig. 18 . Yunnan ............ A. schuelkei sp.n.

6 Median lobe with rounded apex.......................................................................... 7

- Median lobe with subacute or narrowly arcuate apex.......................................................... 8

7 Parameres considerably exceeding apex of median lobe, basal portion of internal sac without oval structure ( Fig. 22–23 ). Head, pronotum and abdomen reddish-brown, elytra yellow-brown to brown. Body length: 2.81–3.75 mm. Habitus as in Fig. 17 . Sichuan ........................................................................... A. rotundatum sp.n.

- Parameres moderately exceeding apex of median lobe, basal portion of internal sac with oval structure ( Fig. 39–40 ). Forebody yellow-brown, abdomen reddish-brown. Body length:3.20–3.85. Habitus as in Fig. 34 . Tibet ............ A. tibetanum sp.n.

8 Anterior angles of pronotum distinctly protruded anteriad. Median lobe with subacute apex; internal sac with ring-like structure in basal part ( Figs. 8–9 ). Body length:3.55–4.95. Habitus as in Fig. 2 . Yunnan ...................... A. assingi sp.n.

- Anterior angles of pronotum not protruded anteriad. Median lobe with narrowly arcuate apex; internal sac without ring-like structure in basal part.................................................................................. 9

9 Median lobe narrow; parameres short, reaching apex of median lobe (see Watanabe 1999: Fig. 2 ). Body length: 2.80–3.20 mm. Habitus (see Watanabe 1999: Fig. 1 ). Guangxi .................................... A. miaoershanum Watanabe, 1999

- Median lobe wider; parameres longer, distinctly exceeding apex of median lobe................................... 10

10 Apical portion of median lobe wide; parameres relatively wide ( Fig. 37 ). Body length:3.50–4.80. Habitus as in Fig. 33 . Sichuan ............................................................................... A. subelongatum sp.n.

- Apical portion of median lobe narrow; parameres narrow..................................................... 11

11 Elytra slightly wider than long. Aedeagus narrow; basal portion of internal sac with wide field of large thorns ( Fig. 35 ). Body length: 2.90–4.00 mm. Habitus as in Fig. 32 . Shaanxi .......................................... A. subaequale sp.n.

- Elytra slightly longer than wide. Aedeagus wider basally; basal portion of internal sac with very wide, strongly sclerotized thorns ( Fig. 27 ).Body length:2.90–3.95. Habitus as in Fig. 19 . Sichuan ............................ A. squamosum sp.n.

Figures

FIGURES 12–15.Aedeagus of Amphichroum longilobatum sp.n.(12–13: paratype) and A. maculosum sp.n. (14–15: paratype): 12, 14–parameral view, 13, 15–lateral view. Scale bar: 0.1 mm.

FIGURES 1–4. Habitus of Amphichroum (males): 1–A. angustilobatum sp.n. (holotype), 2–A. assingi sp.n. (holotype), 3–A. longilobatum sp.n. (paratype), 4–A. maculosum sp.n. (holotype). Scale bar: 1.0 mm.

FIGURES 20–23. Aedeagus of Amphichroum propinquum sp.n.(20–21: holotype) and A. rotundatum sp.n. (22–23: paratype): 20, 22–parameral view, 21, 23–lateral view. Scale bar: 0.1 mm.

FIGURES 16–19. Habitus of Amphichroum (males): 16–A. propinquum sp.n. (holotype), 17–A. rotundatum sp.n. (holotype), 18–A. schuelkei sp.n. (paratype), 19–A. squamosum sp.n. (holotype). Scale bar: 1.0 mm.

FIGURES 5–10. Aedeagus of Amphichroum angustilobatum sp.n.(5–7: holotype) and A. assingi sp.n. (8–10: paratype): 5, 8– parameral view (outline of internal sac shown as point line), 6, 9–internal sac, 7, 10–lateral view. Scale bar: 0.1 mm.

FIGURES 24–28. Aedeagus of Amphichroum schuelkei sp.n.(24–26: paratype) and A. squamosum sp.n. (27–28: paratype): 24 (outline of internal sac shown as point line), 27–parameral view, 25–internal sac, 26, 28–lateral view. Scale bar: 0.1 mm.

FIGURES 39–40. Aedeagus of Amphichroum tibetanum sp.n. (paratype): 39—parameral view, 40—lateral view. Scale bar: 0.1 mm.

FIGURES 32–34. Habitus of Amphichroum (males): 32—A. subaequale sp.n. (paratype), 33—A. subelongatum sp.n. (paratype), 34—A. tibetanum sp.n. (holotype). Scale bar: 1.0 mm.

FIGURES 35–38. Aedeagus of Amphichroum subaequale sp.n. (35–36: paratype) and A. subelongatum sp.n. (37–38: paratype): 35, 37—parameral view,36, 38—lateral view. Scale bar: 0.1 mm.