Key to species of Orionis

1. Face, pronotum and propleuron yellow....................... Orionis orientalis Shaw & Shimbori sp. nov. (Thailand)

- Face, pronotum and propleuron black or brown............................................................ 2

2. Female flagellum with 20 segments; dorsal face of propodeum gently curved into posterior face, in profile propodeum curved; pronotum smooth and polished except for rugose pronotal furrow........... O. ecuadoriensis Shaw & Shimbori sp. nov.

- Female flagellum with 21–25 segments; dorsal face of propodeum abruptly bent into posterior face, in profile propodeum in angle near 90°; pronotum mostly rugose-costate............................................................ 3

3. Mesonotum with evident, although frequently low, median longitudinal carina; scutellar sulcus with median and two lateral carinae (4-foveate)......................................................... Orionis eximius (Muesebeck, 1955)

- Mesonotum without a median carina; scutellar sulcus with median carina only (2-foveate).......................... 4

4. Mid legs yellowish to light brown; female with hind coxa yellowish brown and mesosoma mostly reddish brown. Petiole smooth and its length is 0.8 × mesosoma length....................................... .. Orionis masoni Shaw, 1987

- Mid legs with femur black; female with hind coxa mostly black and mesosoma entirely black. Petiole striate on apical half and its length is 0.6 × mesosoma length............ .. Orionis brasilensis Bortoni, Souza-Gessner & Penteado-Dias sp. nov.