Key to the adults of Cultroribula in Mongolia

1 Legs tridactylous; lamellar cusp longer, but slightly narrower than basal part of lamella, with distal tooth................ 2

– Legs monodactylous; lamellar cusp shorter, but wider than basal part of lamella, without distal tooth.................................................................................................. C. berolina Weigmann, 2006

2 Genital plates with five or six pairs of setae; if lamellar cusp with distal teeth, then median tooth conspicuously developed.. 3

– Genital plates with four pairs of setae; lamellar cusp without inner tooth......................... C. rarisetosa sp. nov.

3 Interlamellar seta long, extending tip of lamellar cusp......................................................... 4

– Interlamellar seta short, not reaching base of lamellar cusp..................................................... 5

4 Tip of rostrum with large teeth deeply incised in-between; interlamellar seta barbed, reaching tip of rostrum; humeral process projected distally............................................................. C. taigagica Bayartogtokh, 2007

– Tip of rostrum with small teeth of similar size, without deep incision; interlamellar seta smooth, not reaching tip of rostrum; humeral process rounded........................................................... C. dentata Willmann, 1950

5 Sensillus fusiform, with very long setiform tip; rostrum with 15–17 teeth, among them three central teeth much larger than lat- eral teeth.............................................................................. C. altaica sp. nov.

– Sensillus clavate or fusiform, without long setiform tip; rostrum with 17 teeth, among them five central teeth much larger than lateral teeth.................................................................... C. vtorovi Krivolutsky, 1971