Key to males of the Lucanus boileaui group

1. Large sized species that can reach more than 60 mm in length; clypeolabrum tongue shaped and long (Fig. 2T); dorsal surface of the body with long yellow brown pubescence (Fig. 1G); all tibiae with bright yellowish brown stripes (Fig. 2V–X); flagellum very long (Fig. 4D), usually 8–10 times longer than aedeagus........................... Lucanus boileaui Planet, 1897

– Smaller sized species than cannot reach more than 50 mm; clypeolabrum not tongue shaped and short (Fig. 2B, H); dorsal surface of the body with fine and visible short pubescence or nearly smooth (Fig. 1A, C); all tibiae black (Fig. 2D–F, J–L), without bright yellowish brown stripes; flagellum shorter (Fig. 4A–B), about 2–3 times longer than aedeagus............. 2

2. Each mandible usually with 3–7 inner teeth (excluding apical fork), major inner tooth behind the middle, distinctly near the base, apical fork developed (Fig. 2G); dorsal surface of the body with fine and visible short pubescence (Fig. 1C); penis narrower (Fig. 4I); flagellum (Fig. 4B) about 2.5 times longer than aedeagus........... .. Lucanus ludivinae Boucher, 1998

– Each mandible usually with 1–4 inner teeth (excluding apical fork), major inner tooth at the middle, apical fork less developed (Fig. 2A); dorsal surface of the body nearly smooth (Fig. 1A), without visible pubescence; penis wider (Fig. 4E); flagellum (Fig. 4A) about 2.0 times longer than aedeagus.................... Lucanus jiaozishanus Qi, He, Su & Song, new species