Key to species (males) of Pachymetopius, modified from Wei et al. (2008)

1. Anteclypeus narrow basally, thereafter gradually and evenly broadening from base to sub-apex, then abruptly expanded apically .......................................................................................................................................................................................... P. decoratus

- Anteclypeus broadly convex basally (Fig. 5) .................................................................................................................................... 2

2. Aedeagus without lateral processes................................................................................................................................................... 3

- Aedeagus with pair of lateral processes ............................................................................................................................................ 4

3. Aedeagal shaft narrow with lateral margin sinuate in posteroventral view ................................................................... P. bicaudatus

- Aedeagal shaft broad, strongly constricted subbasally in posteroventral view.............................................................. P. bicornutus

4. Aedeagal processes distinctly shorter than shaft (Figs. 9-10) ........................................................................................................... 5

- Aedeagal processes similar in length to shaft ................................................................................................................................... 6

5. Aedeagal shaft constricted subapically in ventral view (Fig. 9); outer apical style process narrow (Fig.12); pygofer side with inner process hook shaped (Fig. 6) ................................................................................................................................. P. falcatus sp. nov.

- Aedeagal shaft not constricted subapically in ventral view; outer apical style process broad; pygofer side with inner process lobelike ............................................................................................................................................................................... P. nanjingensis

6. Aedeagal processes with denticles; pygofer process bifurcate apically ............................................................................. P. dentatus

- Aedeagus processes without denticles; pygofer process not bifurcate apically ................................................................. P. curvatus