1. Dorsum of segment 10 bearing hemitergal lobes. . . . . . . . . . . . . . . . . . . . . . . . . Males, 2
Dorsum of segment 10 without hemitergal lobes . . . . . . . . . . . . . . . . . . . . . . . Females, 9
2. Mesal sclerite of tergum 8 abruptly elevated on posterior margin in lateral aspect; aedeagal tube with external spines; sac densely armed with small spicules and larger spines . . . . . . . . . . 3
Mesal sclerite of tergum 8 rounded in lateral aspect; aedeagal tube without external spines, small spicules present or absent; sac sparsely armed with scattered spines. . . . . . . . . . . . . . . . 4
3. Aedeagal sac with few large spines beyond basal arc; head mostly dark with a pair of pale spots between eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neoperla gaufini
Aedeagal sac with at least 10 moderate to large spines beyond basal arc; head without pale spots between eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. catharae
4. Aedeagal tube bent abruptly dorsad near midlength . . . . . . . . . . . . . . . . . . . . N. robisoni
Aedegal tube straight or slightly sinuate, without abrupt bend near midlength . . . . . . . . . . 5
5. Aedeagal tube slender, tube length at least 4 times bulb length . . . . . . . . . . . . . . . . . . . 6
Aedeagal tube plump, tube length less than 4 times bulb length . . . . . . . . . . . . N. stewarti
6. Dorsum of aedeagal tube with inconspicuous spicules; ventoapical margin of tube extends over base of sac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. clymene
Dorsum of aedeagal tube with prominent spicule patch; ventroapical margin of tube not overlapping sac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Aedeagal tube spicules prominent on subapical knob; tube more than 6 times bulb length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. mainensis
Aedeagal tube spicules form large dorsolateral patch; tube 4-5 times bulb length . . . . . . . 8
8. Aedeagal sac armature prominent; aedeagal tube apex not conspicuously narrowed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. coosa
Aedeagal sac armature obscure; aedeagal tube apex distinctly narrowed . . . . . N. occipitalis
9. Females. Spermathecal stalk short and almost completely lined with paralelle rows of brown setae; anteromesal margin of sternum 8 without a membranous notch . . . . . . . . . . . . . . . . . 10
Spermathecal stalk long, coiled and incompletely lined with brown setae; anteromesal margin of sternum 8 with a membranous notch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
10. Egg collar present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. catharae
Egg collar absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. gaufini
11. Posteromesal margin of sternum 8 not projecting beyond posterolateral margins . . . . . 12
Postereromesal margin of sternum 8 projecting beyond posterolateral margins . . . . . . . 13
12. Essentially no posteromesal subgenital plate development; spermatecal stalk lining narrow and restricted to apical third of stalk; egg uslci about as wide as striae . . . . . . . . . . N. clymene
Subgenital plate small, rounded and slightly recessed below poeterolateral margins of sternum 8; spermathecal stalk lining broad apically and extending fom basal third to half of stalk; egg striae wide, separated by narrow sulci . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. coosa
13. Spermathecal stalk lining restricted to a small apical patch . . . . . . . . . . . . . . . N. stewarti
Spermathecal stalk lining covering at least apical third of stalk . . . . . . . . . . . . . . . . . . 14
14. Subgenital plate triangular and about as long as wide . . . . . . . . . . . . . . . . . N. mainensis
Subgenital plate small and truncate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
15. Spermathecal stalk lining truncate apically and with ca 3 dark longitudinal folds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N. robisoni
Spermathecal stalk lining rounded apically and without dark longitudinal folds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. occipitalis
Key to the Adult Neoperla of Ohio