Key to described Nealyda species in the United States based on male genitalia

1. Vincular processes longer than wide; saccular processes triangular............. phytolaccae group, 2

— Vincular processes extremely small, weakly sclerotized bumps bearing few setae directly below saccular processes; saccular processes ovate in outline with cuspidate or hooked apex... pisoniae group, 3

2(1). Vincular processes long, with pointed apex and with few setae; saccular processes large and mitten-shaped, extending slightly beyond length of saccular processes; phallus slightly curved............................................................................ N. phytolaccae Clarke

— Vincular processes small, digitiform, rounded projections not extending beyond apex of vinculum; saccular processes with blunted apex and many setae; phallus sharply curved..... N. bifidella Dietz

3(1). Saccular processes with strongly sclerotized apical hook; phallus narrow, bent to curved with no spines.................................................................................... 4

— Saccular processes bluntly rounded with small apical spine and many apical setae; phallus broad and spinose............................................ N. grandipinella Bennett and Hayden

4(3). Apices of valvae slightly pointed; saccus sharply pointed; phallus bent at 90° angle...................................................................................... N. kinzelella Busck

— Apices of valvae rounded; saccus rounded to weakly pointed; phallus slightly curved..................................................................................... N. pisoniae Busck