Key to known species of Tritegeus (= Sphodrocepheus)

1. All legs monodactylous; cusp of lamella dentate laterally; body length: 700–714.......................................................................... Tritegeus dentatus (Fujikawa, 1972) . Distribution: Eastern Palaearctic region.

- All legs heterotridactylous; cusp of lamella not dentate laterally................................................ 2

2. Bothridial seta setiform or bacilliform, without distinct head (sometimes with unclear thickening)..................... 3

- Bothridial seta with well-developed head.................................................................. 5

3. Rostrum pointed; notogastral seta la inserted posteriorly to c; body length: 725–860....... Tritegeus bisulcatus Grandjean, 1953 (see also S. Bernini & Bernini 1990; Pérez-Íñigo 1997; Weigmann 2006). Distribution: Western Palaearctic region.

- Rostrum rounded; notogastral seta la inserted posterolaterally to c .............................................. 4

4. Bothridial seta long, longer than interlamellar seta; translamella present; body length: 1018......................................................... Tritegeus major Golosova & Karppinen, 1984 . Distribution: Eastern Palaearctic region.

- Bothridial seta medium-sized, shorter than interlamellar seta; translamella absent; body length: 888–990......................... Tritegeus brevisetus Sitnikova, 1975 (in 1975 a). Distribution: Eastern Mediterranean, Eastern Palaearctic region.

5. Cusps of lamellae entirely fused medially; body length: 780–840.................................................................... Tritegeus mitratus (Aoki, 1967) (also data presented here). Distribution: Eastern Palaearctic region.

- Cusps of lamellae entirely or partially separated medially..................................................... 6

6. Interlamellar and dorsal notogastral (c, la, lm, lp, h 2, h 3) setae inserted on strong tubercles; body length: 681.................................................. Tritegeus tuberculatus (Mahunka, 1988) . Distribution: Vietnam, Nepal, Mexico.

- Interlamellar and dorsal notogastral (c, la, lm, lp, h 2, h 3) setae not inserted on strong tubercles........................ 7

7. Centrodorsal part of notogaster simultaneously with areolae and ridges; notogastral seta h 1 swollen distally; body length: 750................................ Tritegeus sculptus S. Bernini & Bernini, 1990 . Distribution: Western Mediterranean.

- Centrodorsal part of notogaster not simultaneously with areolae and ridges; notogastral seta h 1 not swollen distally....... 8

8. Dorsal notogastral setae la, lm, lp, h 2, h 3 medium-sized (as long as distance lm–lp)................................. 9

- Dorsal notogastral setae la, lm, lp, h 2, h 3 long (distinctly longer than distance lm–lp)............................... 10

9. Bothridial seta medium-sized, distinctly shorter than interlamellar seta; posterior notogastral seta p 1 distinctly longer than h 1; notogaster with areolae; body length: 647–747...... Tritegeus janosbaloghi Ermilov & Martens, 2022 . Distribution: Nepal.

- Bothridial seta long, not shorter than interlamellar seta; posterior notogastral setae h 1 and p 1 slightly different in length; notogaster without areolae; body length: 870................................................................................................... Tritegeus anthelionus (Woolley & Higgins, 1968) . Distribution: Nearctic region.

10. Dorsal notogastral setae lp, h 2, h 3 longer (longer than distance lp– h 2), distinctly barbed; posterior notogastral setae h 1 and p 1 slightly different in length; seta v’ on leg tibiae I, II thorn-like; body length: 720–780.............................................. Tritegeus tridactylus (Woolley & Higgins, 1963) (also data presented here). Distribution: Holarctic region.

- Dorsal notogastral setae lp, h 2, h 3 shorter (not longer than distance lp– h 2), roughened, with sparse barbs in distal part; posterior notogastral seta p 1 distinctly longer than h 1; seta v’ on leg tibiae I, II setiform, with ventral sparse spines; body length: 690– 825.................................................... Tritegeus luissantossubiasi sp. nov. Distribution: India.