Key to the species of the kalshoveni species-group

1. Oblique stripe in apical part of forewing short, not crossing M1 vein............................................ 2

-. Oblique stripe in apical part of forewing long, crossing M1 vein and reaching (or almost reaching) external wing margin.. 4

2. Basal quarter of forewing uniformly grey, without scattered dark or light scales...................... N. agassizi Kozlov

-. Basal quarter of forewing patchy, scattered with both dark brown and light (white or yellow) scales.................... 3

3. Forewing grey; its basal half scattered with both dark brown and white scales (approximately in 1:1 ratio); oblique stripe in apical part of forewing white; apex of valva extends beyond apex of tegumen; apex of valva rounded.. N. humerella Kozlov

-. Forewing brown; its basal half scattered with both dark brown and light yellow scales (approximately in 5:1 ratio); oblique stripe in apical part of forewing (at least a part of it) yellow; apex of tegumen extends beyond apex of valva; apex of valva pointed........................................................................... N. kalshoveni Diakonoff

4. Forewing narrow (WLR <0.3); oblique stripe in apical part of forewing reaches external wing margin, where connects to the light spot surrounding wing apex....................................................... N. stenopterella Kozlov

-. Forewing wide (WLR> 0.3); oblique stripe in apical part of forewing does not reach external wing margin and is separated from the light spot surrounding wing apex.................................................................. 5

5. Oblique stripe in apical part of forewing white, not reaching external wing margin; apex of forewing with glossy silver spot; apical segment of PLB white, contrasting to brown basal segments.............................. N. toxopeusi Kozlov

-. Oblique stripe in apical part of forewing ochreous, reaching external wing margin; apex of forewing surrounded by narrow ochreous spot; apical segment of PLB brown, of the same colour as basal segments................................ 6

6. Larger (FWL 4.7–6.5 mm); oblique stripe in apical part of forewing straight; male genitalia of typical size (total length 1.10 mm); length of vinculum approximately twice its width................................................. N. dohertyi Kozlov

-. Smaller (FWL 4.3 mm); oblique stripe in apical part of forewing bent medially; male genitalia very small (total length 0.48 mm); length of vinculum approximately equals its width....................................... N. bistrigata Kozlov