Key to species of the subgenus Gyrostoma from China

1. Metasoma uniformly reddish brown to dark brown. Dorsal episternal groove (Fig. 5 a) or epicnemial carina absent (Fig. 5 a') and area densely punctate. Last visible sternite of male without apophyses (Fig. 5 b)................................. 2

- Metasoma generally black with abundant yellow markings or largely yellow. Dorsal episternal groove and epicnemial carina both present (Fig. 6 aa) and area comparatively sparsely punctate. Last visible sternite of male with apophyses (Fig. 6 bb, bb') (except Polistes tenuispunctia).......................................................................... 3

2. Malar space of female as long as distance from inner edge of one antennal socket to outer edge of other (Fig. 7 a). Parastigma (pa) of fore wing longer than ventral margin of pterostigma (pt) (Fig. 7 b). Dorsal episternal groove absent, epicnemial carina present (Fig. 1 a). Male: mandible (Fig. 7 c) and terminal segment of antenna (Fig. 7 d) modified... P. (G.) gigas (Kirby, 1826)

- Malar space of female shorter than distance from inner edge of one antennal socket to outer edge of other socket (Fig. 8 aa). Parastigma (pa) of fore wing shorter than the ventral margin of pterostigma (pt) (Fig. 8 bb). Dorsal episternal groove present; epicemial carina absent (Fig. 1 a'). Male: mandible (Fig. 8 cc) and terminal segment antenna (Fig. 8 dd) normally shaped............................................................................ P. (G.) tenebricosus Lepeletier, 1836

3. Body generally yellow. Mesopleuron weakly and sparsely punctate medially (Fig. 9 a)................................ 4

- Body black or dark brown with yellow pattern. Mesopleuron strongly and densely punctate medially(Fig. 10 aa)......... 5

4. Female: fore wing length 15 – 28 mm. Body always with black pattern and at least dorsal sulcus of clypeus of female black (Fig. 11 a). Male: clypeus evenly convex (Fig. 11 b). Lateral tubercles on each side of apex of last sternite subtriangular and wider at base (Fig. 11 c), its terminal apophyses long and spatulate apically (Fig. 11 d)............. P. (G.) olivaceus (De Geer, 1773)

- Female: fore wing length 11-17 mm. Body without black pattern, including medial part of dorsal sulcus of clypeus of female (Fig. 12 aa), but sometimes surroundings of ocelli darkened. Male: clypeus with impression (Fig. 12 bb). Lateral tubercles of last sternite more cylindrical and narrower basally (Fig. 12 cc), its terminal apophyses long and pointed apically (Fig. 12 dd)................................................................................. (G.) wattii Cameron, 1900

5. Male: apical 3–4 antennal flagellomeres flattened and curved (Fig. 13 a). Last visible sternite without apophyses (Fig. 13 b). Female: ventral third of occipital carina absent or vestigial (Fig. 13 c) and yellow apical part of first tergite widened laterally (Fig. 13 d), China (Shaanxi).................................................... P. (G.) tenuispunctia Kim, 2001

- Male: antenna generally not curved apically, 3 – 4 apical flagellomeres cylindrical, at most terminal flagellomere spatulate (Fig. 14 aa). Last visible sternite with apophyses (Fig. 14 bb). Female: ventral third of occipital carina variable (Fig. 14 cc), yellow apical part of first tergite parallel-sided laterally (Fig. 14 dd).................................................... 6

6. Female: occipital carina incomplete, not reaching base of mandible (Fig. 15 a). Male: clypeus narrowly separated from eyes (Fig. 15 b). Terminal antennal flagellomere slightly curved and cylindrical (Fig. 15 c). Lateral tubercles of last sternite less protruding (Fig. 15 d), its apophyses short and truncated apically (Fig. 15 e).................. P. (G.) jokahamae Radoszkowski, 1887

- Female: occipital carina complete, reaching base of mandible (Fig. 16 aa). Male: clypeus touching eyes (Fig. 16 bb). Terminal antennal flagellomere spatulate, flattened and widened (Fig. 16 cc). Lateral tubercles of last sternite distinctly protruding (Fig. 16 dd), its apophyses long and narrow (Fig. 16 ee)................................... P. (G.) rothneyi Cameron, 1900