Megalotomus castaneus Reuter, 1888

(Figs. 14–16, 32–34)

Megalotomus castaneus Reuter, 1888: 66 . Lectotype (Kerzhner, 1972: 352, as Holotype): ♀, China (North), Beijing; MNHN. Hsiao, 1977: 276–277; Nonnaizab et al., 1986: 305–313; Nonnaizab, 1999: 76–77; Dolling, 2006: 38; Huang et al, 2013: 135–136.

Diagnosis. This species is recognized within the genus Megalotomus by a combination of the following characters: body relatively large, 15.0–17.0 mm in length, mostly brownish in colour; vertex black, with pale yellow midline; pronotum divided into two lobes by colour, with anterior lobe black, and posterior lobe reddish brown; posterior angles of pronotum acute and pointed, with a sharp apex; surcapsular spines of the genital capsule slightly curving, each one with a broad spine at outer margin of proximal part and a small bifurcation at apex; parameres wide and curving, each one with a conspicuous longitudinal crease at the terminal half.

Material examined. China: Hebei Province: 1 ♂, 4 ♀♀, Xiaowutaishan National Nature Reserve, Jinhekou, 1200 m, 26-July-2000, Weibing Zhu leg. (NKUM) ; 1 ♀, ibid, Wenjun Bu leg. (NKUM); 1 ♂, ibid, 1100 m, 23-July-2000, Wenjun Bu leg. (NKUM); 1 ♂, Yuxian County, Xiaowutaishan National Nature Reserve, 1300 m, 2-August-2000, Peng Wang leg. (NKUM) ; 1 ♂, ibid, 26-July-2000, Jincheng Ge leg. (NKUM); 1 ♂, ibid, Shumin Zhou leg. (NKUM); 1 ♀, Xiaowutaishan National Nature Reserve, Songzhikou, 1200 m, 3-August-2000, Weibing Zhu leg. (NKUM) ; Yuxian County, Songzhikou, 1200 m, 3-August-2000, Jincheng Ge leg. (NKUM) . Shanxi Province: 1 ♂, 1 ♀, Yangquan City, Cuifengshan Natural Scenic Spot, 37.79°N, 113.43°E, 1036 m, 22-July-2020, Wenbo Yi leg. (XZTU) ; 2 ♂♂, Lvliang City, Wenyuhe National Wetland Park, 36.43°N, 113.37°E, 654 m, 11-August-2019, Wenbo Yi leg. (XZTU) .

Distribution. China (Beijing, Hebei, Inner Mongolia, Shanxi).

Remarks. Based on distribution data gathered from the literature and studied specimens, M. castaneus and M. acutulus are nearly sympatric. The host plant of M. castaneus remains unknown so far.