Key for the species of Nyetnops Platnick & Lise (males only)

1. Length of copulatory bulb (tegulum + embolus) just two times or less the palpal tibia length (Figs 1 B–D; 4B–C).......... 2

- Length of copulatory bulb (tegulum + embolus) 2.7 or three times the palpal tibia length (Figs 8 B–C; 9B–C)............. 3

2. Tegulum apical section swollen on median portion, width similar to palpal tibia (Figs 4 B–C; 8H), embolus tip with very long rooster’s crest like projections (Fig. 7 A–F)................................................... N. naylienae n. sp.

- Tegulum apical section weakly swollen on median portion, narrower than palpal tibia width (Fig. 1 B–C), embolus tip beveled with short projections (Fig. 3 G–I)................................................................ N. guarani

3. Mid of palpal tibia strongly swollen, 1.8 times wider than proximal and distal portions (Fig. 8 B–C); copulatory bulb slender, weakly swollen on tegulum apical section, only a half palpal tibia width (Fig. 8 B–C).................. N. lachonta n. sp.

- Mid of palpal tibia weakly swollen, only 1.2 times wider than proximal and distal portions (Fig. 9 B–C), copulatory bulb thick, slightly swollen at tegulum apical section and narrow at basal section (Figs 8I; 9 B–C).................... N. buruti n. sp.