1	Male mandibles with dorsal tooth	2
–	Male mandibles without dorsal tooth	9
2	Internal sac of aedeagus with two spines	3
–	Internal sac of aedeagus with one spine	4
3	HL/PL more than 1.00. Male right mandible with small dorsal tooth; internal sac of aedeagus with one long curved spine and one short spine. Posterior margin of female tergite VIII truncate	P. (Gnathopaederus) szechuanus (Chapin, 1927)
–	HL/PL no more than 0.95. Male right mandible with large dorsal tooth; internal sac of aedeagus with two short spines. Posterior margin of female tergite VIII convex	P. (Gnathopaederus) bursavacua Willers, 2001
4	Smaller species, length of body: 7.2 mm. Length of antenna no more than 3.0 mm	P. (Gnathopaederus) jilongensis Li & Zhou, 2009
–	Larger species, length of body more than 8.0 mm. Length of antenna more than 3.3 mm	5
5	Male sternite V–VI with shallow median impression posteriorly, this impression with weakly modified setae	P. (Gnathopaederus) zhangmuensis Cheng & Peng, 2019
–	Male sternite V–VI without median impression and modified setae posteriorly	6
6	Dorsal plate of aedeagus straight in lateral view and internal sac with one short spine	P. (Gnathopaederus) cheni Peng & Li, 2015
–	Dorsal plate of aedeagus weakly curved in lateral view and internal sac with one long spine	7
7	Male left mandible with large dorsal tooth; internal spine of aedeagus apically extending nearly to apex of dorsal plate	P. (Gnathopaederus) furcillatus Assing, 2017
–	Male left mandible with small dorsal tooth; internal spine of aedeagus far from reaching apex of dorsal plate	8
8	Smaller species, length of body: 8.3–10.5 mm. Male right mandible with small dorsal tooth; smaller aedeagus with slenderer parameres	P. (Gnathopaederus) yunnanensis Willers, 2001
–	Larger species, length of body 11.6–12.4 mm. Male right mandible with large dorsal tooth; larger aedeagus with stouter parameres	P. (Gnathopaederus) xuei Peng & Li, 2015
9	Coloration of abdomen black	10
–	Abdomen bicoloured (usually segments III–VI reddish and segments VII–X black)	21
10	Coloration of head brown. Male sternite VI with distinct median impression posteriorly	P.lateralis Li, Solodovnikov & Zhou, 2014
–	Coloration of head black. Male sternite VI without median impression posteriorly	11
11	Male sternite VII with deep median impression posteriorly. Parameres of aedeagus very short	P.mirus Yang & Peng, sp. nov.
–	Male sternite VII without impression posteriorly. Parameres long and conspicuous	12
12	Small species, length of body no more than 8.5 mm	P.sinisterobliquus Li, Zhou & Solodovnikov, 2013
–	Large species, length of body larger than 9.0 mm	13
13	Maximum width of pronotum no more than 1.50 mm. Parameres of aedeagus apically distinctly curved in lateral view	P.chentangus Yang & Peng, sp. nov.
–	Maximum width of pronotum more than 1.54 mm. Parameres of aedeagus apically weakly curved or straight in lateral view	14
14	Internal sac of aedeagus with two spines	15
–	Internal sac of aedeagus with three spines	17
15	Maximum width of abdomen more than 2.1 mm. Parameres of aedeagus slender. Female sternite IX longer	P.parvidenticulatus Li, Zhou & Solodovnikov, 2013
–	Maximum width of abdomen no more than 2.0 mm. Parameres of aedeagus stout. Female sternite IX shorter	16
16	HL/HW more than 0.95. Aedeagus with apically hooked dorsal plate in dorsal view and two long sclerotized spines in internal sac. Female sternite VIII with elliptic depression posteriorly	P.volutobliquus Li, Zhou & Solodovnikov, 2013
–	HL/HW no more than 0.90. Aedeagus with apically acute dorsal plate in dorsal view and two short sclerotized spines in internal sac. Female sternite VIII without depression	P.nanlingensis Peng & Li, 2016
17	Legs with infuscate apical portion of femora. Aedeagus with apically hooked dorsal plate in dorsal view	P.biacutus Li, Zhou & Solodovnikov, 2013
–	Legs with brown femora. Aedeagus with apically acute dorsal plate in dorsal view	18
18	Parameres of aedeagus symmetric and slender in ventral view	P.jianyueae Peng & Li, 2014
–	Parameres of aedeagus asymmetric and stouter in ventral view	19
19	Internal sac of aedeagus with one additional dark membranous structure. Female right mandible with single-pointed middle tooth	P.zhaoi Yang & Peng, sp. nov.
–	Internal sac of aedeagus without dark membranous structure. Female right mandible with small bifid molar tooth apically	20
20	Ventral plate of aedeagus short and broad. Posterior margin of female sternite VIII strongly convex	P.songi Yang & Peng, sp. nov.
–	Ventral plate of aedeagus long and slender. Posterior margin of female sternite VIII distinctly trifurcate	P.trispinosus Yang & Peng, sp. nov.
21	Aedeagus stout, with short and stout dorsal plate in dorsal view	22
–	Aedeagus slender, with long and slender dorsal plate in dorsal view	24
22	Legs reddish with infuscate apical portion of femora. Aedeagus with apically acute dorsal plate in dorsal view	P.tibetanus Cameron, 1928
–	Legs yellowish brown. Aedeagus with apically convex dorsal plate in dorsal view	23
23	Male labrum with sinuate anterior margin. Aedeagus with short parameres. Female sternite VIII with truncate median process posteriorly	P.describendus Willers, 2001
–	Male labrum with deeply excavate anterior margin. Aedeagus with long parameres. Posterior margin of female sternite VIII convex	P.daicongchaoi Peng & Li, 2016
24	Dorsal plate of aedeagus not reaching apices of parameres	25
–	Dorsal plate of aedeagus extending beyond apices of parameres	29
25	Segments III–VI of abdomen reddish and with black patch in middle; elytra with pronounced impression	P. (Harpopaederus) gottschei Kolbe, 1886
–	Segments III-VI of abdomen pale-reddish and without black patch in middle; elytra without impression	26
26	Dorsal plate of aedeagus without denticles	P. (Harpopaederus) antennocinctus Willers, 2001
–	Dorsal plate of aedeagus with conspicuous denticles	27
27	Internal sac of aedeagus with one long and apically acute moderately sclerotized structure	P. (Harpopaederus) willersi Assing, 2020
–	Internal sac of aedeagus with one basal clip-shaped structure and one asymmetric apical structure	28
28	Length of aedeagus: 2.4 mm. Female tergite VIII apically narrower	P. (Harpopaederus) deplectens Assing, 2015
–	Length of aedeagus: 2.7 mm. Female tergite VIII apically broader	P. (Harpopaederus) chinensis Bernhauer, 1931
29	Dorsal plate of aedeagus without denticles	30
–	Dorsal plate of aedeagus with denticles	31
30	Length of aedeagus: 1.4 mm; internal sac without sclerotized basal structures	P. (Harpopaederus) xui Peng & Li, 2015
–	Length of aedeagus: 2.0 mm; internal sac with one clip-shaped, weakly sclerotized basal structure	P. (Harpopaederus) edentulus Assing, 2015
31	Legs with blackish metatibiae	32
–	Coloration of metatibiae much paler (usually yellowish)	33
32	Length of aedeagus: 2.4–2.7 mm, with apically stouter dorsal plate. Female sternite VIII with short median process posteriorly	P. (Harpopaederus) apfelsinicus Willers, 2001
–	Length of aedeagus: 2.9 mm, with apically more slender dorsal plate. Female sternite VIII with long median process posteriorly	P. (Harpopaederus) lineodenticulatus Li & Zhou, 2007
33	Forebody longer than 5.8 mm. Aedeagus conspicuously long (2.7 mm)	P. (Harpopaederus) minicus Assing, 2015
–	Forebody no more than 5.5 mm. Aedeagus shorter	34
34	Internal sac of aedeagus with one long, apically acute and sclerotized apical structure	35
–	Internal sac of aedeagus without distinctly sclerotized apical structure	38
35	Aedeagus 2.4 mm long, with longer apical portion of the dorsal plate	P. (Harpopaederus) cultellatus Assing, 2015
–	Aedeagus 1.9–2.1 mm long, with shorter apical portion of the dorsal plate	36
36	Dorsal plate of aedeagus with hooked apex. Posterior margin of female sternite VIII trifurcate	P. (Harpopaederus) yei Yang & Peng, sp. nov.
–	Dorsal plate of aedeagus with acute apex. Female sternite VIII posteriorly with median process of triangular shape	37
37	Tibiae usually yellowish; mandibles and shape of head without sexual dimorphisms. Aedeagus with moderately sclerotized apical internal structure	P. (Harpopaederus) agnatus Eppelsheim, 1889
–	Tibiae distinctly infuscate basally; mandibles and shape of head with pronounced sexual dimorphisms. Aedeagus with strongly sclerotized apical internal structure	P. (Harpopaederus) konfuzius Willers, 2001
38	Femora brown. Dorsal plate of aedeagus with 20 small denticles; parameres apically weakly curved in lateral view	P. (Harpopaederus) multidenticulatus Li, Zhou & Solodovnikov, 2014
–	Femora bicoloured. Dorsal plate of aedeagus with several large denticles; parameres apically hooked in lateral view	39
39	Head transverse (HL/HW: 0.90). Dorsal plate of aedeagus with short apical portion. Female sternite VIII with strongly convex posterior margin	P. (Harpopaederus) brevior Li, Zhou & Solodovnikov, 2014
–	Head weakly transverse (HL/HW: 0.99). Dorsal plate of aedeagus with long apical portion. Female sternite VIII with long median process posteriorly	P. (Harpopaederus) gracilacutus Li & Zhou, 2007