Key to Oriental species of the genus Eridolius

1. Metasoma beyond T1 reddish (figs 5, 10, 11, 13, 17).......................................................... 2

- Metasoma entirely black or black with yellow posterior margins of T1 to T7 (Figs 18, 22, 29, 31, 34)................... 3

2. Upper mandibular tooth longer than lower one (Fig. 15). Malar space 0.5 × as long as basal width of mandible. Face yellow (Fig. 15). Middle and hind coxae, and hind femur black (Fig. 17)........................... E. aithogaster Gupta, 1991

- Lower mandibular tooth longer than upper one (Fig. 3). Malar space 0.3 × as long as basal width of mandible. Face black (Fig. 1). Coxae and hind femur reddish (fig. 5)............................................. E. xui Reshchikov, sp. nov.

3. Body entirely black (figs 30–34).......................................................... E. niger Gupta, 1991

- Body mostly black, with yellow colouration (clypeus, mandibles, most of legs and hind margin of T2-7) (Figs 18–29)...... 4

4. Lower mandibular tooth just slightly longer than upper one (Fig. 27)............................................. 5

- Lower mandibular tooth distinctly longer than upper one (Fig. 20)............................................... 6

5. Fore and middle coxae and all trochanters yellow, hind legs reddish except hind tibia, tarsus and apical part of femur brown (Fig. 29). T1 without flanges at glymmas............................................ E. kambaiti Kasparyan, 1998

- All coxae and hind legs entirely black. T1 with weak flanges over glymmas..................... E. sinensis Gupta, 1993

6. Face and lower part of mesopleuron densely and distinctly punctate. Inter-ocellar distance 0.7 × ocellocular distance. Fore and middle coxae and trochanters yellowish-brown......................................... E. clauseni (Kerrich, 1962)

- Face and lower part of mesopleuron sparsely and shallowly punctate (Fig. 20). Inter-ocellar distance 0.5 – 0.56 × ocellocular distance. Fore and middle coxae and trochanters whitish-yellow (fig. 22)......................... E. guptai Gupta, 1991