Key to the species of the genus Diduga in Vietnam based on the male genitalia

1 Valva symmetric............................................................................. D. alternota

- Valva asymmetric..................................................................................... 2

2 Apex of valva with spines.............................................................................. 3

- Apex of valva without spines............................................................................ 4

3 Uncus stout; apex of valva with a row of 3˗4 strong chaetae are shorter than width of apex valva; basal pro- cesses of valva absent......................................................... D. cucphuonga

- Uncus slender; apex of valva with strongest 2˗3 apical chaetae are longer than width of apex valva; two asymmetric, stout basal processes of valva present............................................. D. nigridentata n. sp.

4 Right valva branched to five diverse sized and formed branches, which are more or less straight on right valva................................................................. D. quinquicornuta n. sp.

- Right valva not branched to five diverse sized and formed branches, which at least one is curved on right valva................................................................................. 5

5 Sclerotized basal part of valva not curved, with broadly waved apical............................ D. hanoiensis n. sp.

- Sclerotized basal part of valva strong curved, with cockcomb˗shaped apical..................... D. bayartogtokhi n. sp.