Key to Pristaulacus species from Vietnam

1. Occipital margin straight or weakly concave, without medial groove (Figs 4A, 6A, 8A, 10A)......................... 2

- Occipital margin deeply concave, with medial more or less pronounced groove (Figs 2A, 12A, 14A, 16A) ( comptipennis species group)........................................................................................ 5

2. Mesosoma yellow without any blackish spot; mesonotum in dorsal view with shallow median longitudinal impression and indistinctly dividing into lateral lobes (Fig. 4D); petiole robust, 1.9 × as long as its apical width (Fig. 4G)................................................................................... P. bicoloratus Long & Jennings, sp. nov.

- Mesosoma black; mesonotum in dorsal view with deeper median longitudinal impression and distinctly dividing into lateral lobes (Figs 6D, 8D, 10D); petiole slender or elongate, 3.0–5.5 × as long as its apical width (Fig. 9A)................... 3

3. Occipital margin straight (Fig. 8A); scape black; fore wing with dark brown substigmal spot, hyaline apically (Fig. 8I); metasoma entirely black (Fig. 8G); petiole 3.1 × as long as its apical width; ovipositor slightly longer than metasoma; body length 8.0 mm............................................................. P. diffusus Long & Turrisi, sp. nov.

- Occipital margin slightly roundly or angularly concave medially (Figs 6A, 10A); scape yellow; fore wing with large dark brown substigmal spot, infuscate apically (Figs 6H, 10I); metasoma reddish-yellow ventrally (Figs 5A, 9D); ovipositor slightly shorter than metasoma....................................................................................... 4

4 Pedicel and clypeus yellow; occipital carina lamelliform and slightly roundly concave medially (Fig. 10A); occipital carina 0.2 × diameter of an ocellus; in lateral view, mesoprescutum protruding anteriorly and distinctly overhanging pronotum, in dorsal view with deep median longitudinal impression and two anterior lobes; fore wing with vein 2-Rs+M long, discal cell elongate (Fig. 10I); hind tarsal claw with five tooth-like processes (Fig. 10H); petiole elongate, 5.5× as long as its apical width; body length 15.3 mm ...................................................... P. mellosus Turrisi, Long & Pham, sp. nov.

- Pedicel and clypeus brown; occipital carina lamelliform and slightly angularly concave medially (Fig. 6A); occipital carina 0.4 × diameter of an ocellus; in lateral view, mesoprescutum round anteriorly, not overhanging pronotum, in dorsal view with shallow median longitudinal impression; fore wing with vein 2-Rs+M short, discal cell more or less quadrate (Fig. 6H); hind tarsal claw with three tooth-like processes (Fig. 6F); petiole 3.5 × as long as its apical width; body length 10.8 mm ............................................................................. P. chumomrayi Long & Turrisi, sp. nov.

5. Pronotum, in lateral view, with two projecting tooth-like processes (see Figs 7 and 50 in Turrisi & Smith 2011)........... 6

- Pronotum, in lateral view, with one projecting tooth-like process (Figs 2E, 12E, 14E; see Fig. 104 in Turrisi & Smith 2011).. ................................................................................................... 7

6. Mesoprescutum slightly extending anteriorly above pronotum and mostly on the same level as mesonotum in lateral view; fore wing vein 2-Rs+M long, discal cell elongate; scape entirely dark brown (female). China, Vietnam .................................................................................................... P. asiaticus Turrisi & Smith

- Mesoprescutum distinctly extending anteriorly above pronotum and on a level higher than mesonotum in lateral view; fore wing vein 2-Rs+M short, discal cell more or less quadrate; scape yellow ventrally, brown dorsally (female). Vietnam ....................................................................................... P. emarginaticeps Turner

7. Occipital carina complete, not interrupted along median groove (see Figs 55, 100 in Turrisi & Smith, 2011).............. 8

- Occipital carina incomplete, interrupted along median groove (Figs 2A, 12A, 14A, 16A; see Fig. 145 in Turrisi & Smith, 2011)............................................................................................... 9

8. Occipital medial groove nearly V-shaped, moderately deep (see Fig. 100 in Turrisi & Smith 2011); fore wing vein 2-Rs+M rather long (see Fig. 105 in Turrisi & Smith 2011); hind basitarsus slender, 11.1 × longer than wide; hind tarsus yellow; metasomal tergite 2 yellow basally; ovipositor 1.2 × fore wing length. Vietnam (Ha Tinh and Ninh Binh provinces)...................................................................................... P. lagrecai Turrisi & Smith

- Occipital medial groove U-shaped, wide and deep (Fig. 55 in Turrisi & Smith 2011); fore wing vein 2-Rs+M rather short (see Fig. 60 in Turrisi & Smith 2011); hind basitarsus 9.9 × longer than wide; hind tarsus reddish brown; metasomal tergites 1 and 2 with orange spots; ovipositor 1.3 × fore wing length. Vietnam (Hoa Binh province).................. P. excisus Turner

9. Fore wing vein 2-RS+M very short, discal cell almost quadrate (Figs 12I, 17B)................................... 10

- Fore wing vein 2-RS+M longer, discal cell elongate (Figs 2I, 14I; see Fig. 150 in Turrisi & Smith 2011)............... 11

10. In lateral view, pronotum with one obtuse projecting tooth-like process anteriorly (Fig. 16E), and with tubercle prominence posteriorly (Fig. 17A); mesoprescutum protruding anteriorly and distinctly overhanging pronotum (Fig. 17A); hind tibial spurs curved (Fig. 16H); petiole distinctly widened apically, length of petiole 5.0 × its apical width dorsally (Fig. 15); scape brown (Fig. 16B); fore wing mostly dark, largely infuscate, with large blackish-brown substigmal spot (Figs 15A, 17B); metasomal tergites 2–4 dark brown ventrally (Fig. 17C).................................. P. tranganicus Long & Pham, sp. nov.

- In lateral view, pronotum with one long projecting tooth-like process (Fig. 12E), and without tubercle prominence posteriorly; mesoprescutum roundly anteriorly and not overhanging pronotum; hind tibial spurs straight (Fig. 12H); petiole slightly widened apically, length of petiole 5.4 × its apical width dorsally (Fig. 12J); scape yellow (Fig. 12B); fore wing mostly yellow, with smaller brownish-yellow substigmal spot (Fig. 12I); metasomal tergites 2–4 reddish-yellow ventrally (Fig.11)........................................................................................... P. phiaoacus Long, sp. nov.

11. Head from above as wide as long (Fig. 2A); occipital carina width 0.3 × diameter of an ocellus; fore wing without dark brown substigmal spot (Fig. 2I); vein 1cu-a of fore wing postfurcal (Fig. 2I); hind femur yellow; metasoma yellow ventrally (male)................................................................................... P. alius Long, sp. nov.

- Head from above 1.1–1.3 × wider than long (Fig. 14A; see Fig. 145 in Turrisi & Smith 2011); occipital lamella width 0.5–0.6 × diameter of an ocellus; fore wing with large dark brown substigmal spot, slightly infuscate apically (Fig. 14J; Fig. 150 in Turrisi & Smith 2011); vein 1cu-a of fore wing interstitial; hind femur black; metasoma entirely blackish or nearly so.......... 12

12. Head from above 1.3 × wider than long, temple roundly narrowed posteriorly (Fig. 145 in Turrisi & Smith 2011); POL: OOL= 1.1; fore leg, except coxa, reddish orange; basal and distal third of mid tibia reddish orange; hind tibia yellowish orange................................................................................ P. vietnamensis Turrisi & Smith

- Head from above 1.1 × wider than long, temple obliquely narrowed posteriorly (Fig. 14A); POL: OOL= 0.9; fore leg, except coxa, yellow; mid tibia yellow, brown dorsally; hind tibia blackish brown.... P. simulatus Long, Jennings & Turrisi, sp. nov.