Key to species of Protomicroplitis

1 Head (except for yellow-orange clypeus, labrum, and mandibles) and mesosoma entirely black (Figs 3–5, 8, 9); male with same coloration on metasoma than female; body and fore wing length almost always 5.0 mm or more (body length average: 5.1 mm, range: 4.7–5.5 mm; fore wing length average: 5.0 mm, range: 4.7–5.2 mm); metatibia almost always over 1.96 mm (very rarely 1.92 mm) [Nearctic species: northern Mexico, US (north of Gainesville, FL), Canada]........................................................................................... Protomicroplitis calliptera (Say, 1836)

- Head and/or mesosoma mostly to entirely orange or yellow (Figs 11, 12, 15, 16, 18, 20, 21, 23, 24, 25–29); male with darker coloration on metasoma than female (Figs 25–29); body length rarely reaching 5.0 mm (usually 4.8 mm or less), fore wing at most 4.8 mm (usually 4.4–4.5 mm); metatibia almost always below 1.85 mm (rarely up to 1.90 mm) [Neotropical species: US (south of Gainesville, FL), Cuba, southern Mexico, Costa Rica]................................................ 2

2(1) Head mostly black (except for orange spot centrally on face, and yellow-orange clypeus, labrum and mandibles) (Figs 12, 15); metatibia yellow-brown on anterior 0.8 ×, posterior 0.2 × (rarely up to 0.4 ×) black (Fig. 11); fore wing mostly to entirely hyaline (Fig. 13); pterostigma with anterior 0.5 yellow in female and male specimens; T1 relatively wider centrally, its width at half length of tergite 0.6–0.7 × its width at anterior margin (Fig. 17) [Central America species: Costa Rica, Turrialba; Mexico: Chiapas, and Quintana Roo]...................... Protomicroplitis centroamericanus Fernandez-Triana new species

- Head entirely orange (Figs 18, 20, 21, 23, 25, 26, 29); metatibia entirely dark brown to black (Figs 18, 26, 27); fore wing infumated (Figs 19, 28); pterostigma entirely brown in females (Fig. 19), mostly brown in males (rarely male specimens with brown coloration restricted to posterior 0.5 of pterostigma) (Fig. 28); T1 relatively narrower centrally, its width at half length of tergite 0.4–0.5 × its width at anterior margin (Fig. 22) [Caribbean and southern Florida species: Cuba, US (FL, south of Gainesville)]....................................................... Protomicroplitis mediata (Cresson, 1865)