Males
1. Ocelli connected with black V or enclosing more or less dark area . . . . . . . . . . . . . . . . . . . . . 4
Ocelli not connected with black V nor enclosing more or less dark area; dorsum of head mostly yellow except for black areas immediately around ocelli . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Vesicle of 8th abdominal sternite longer than broad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Vesicle of 8th abdominal sternite broader than long . . . . . . . . . Isoperla bilineata, I. burksi
3. Vesicle of 8th abdominal sternite deeply recessed, long and narrow . . . . . . . . . . . . . . I. dicala
Vesicle of 8th abdominal sternite mearly a small knob in middle of posterior margin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. decepta
4. Paraprocts little modified, scarcely sclerotized, projecting caudad, up-curved little or not at all . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Paraprocts modified, sclerotized, recurved upward and , in some specimens, forward . . . . . . . 5
5. Paraprocts long, cylindrical, slender, sharp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Paraprocts short, flattened . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Longitudinal dark stripes on abdomen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. transmarina
Abdomen uniformly brown or yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Dorsom of head, thorax and abdomen predominantly yellow, ocellar triangle completely dark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. holochlora
Brownish or yellowish; ocellar triangle has light spot in center in most individuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I. signata
8. Length to apex of wing tips less than 7 mm; predominantly dark brown, except for prothoracic stripe and (in most specimens) light ocellar spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. nana
Length to apex of wing tips greater than 7 mm; most specimens yellowish or brown; all with prothoracic stripe and light ocellar spot; over 11 mm long; without dark patches or setae on 9th and 10th abdominal tergites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. montana
Females
1. Ocelli connected by black V or enclosing a more or less dark area . . . . . . . . . . . . . . . . . . . . . 4
Ocelli not connected by black V nor enclosing a more or less dark area; dorsum of head yellow, except for dark areas around ocelli in some specimens; very faint line connects lateral ocelli with median ocellus in some specimens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Subgenital plate very slightly produced caudad; broadly rounded . . . . . . . . .Isoperla decepta
Subgenital plate much produced caudad; subtriangular . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Margins of subtrianular subgenital plate somewhat incurved before apex . . . . . . . . . I. dicala
Margins of subtriangular subgenital plate straight or somewhat out-curved before apex; apex slightly emarginated in some specimens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. bilineata
4. Species mainly yellow, with lateral ocelli connected to median ocellus by a dark-brown V . . . . .5
Most species fuscous to brown, ocellar triangle all dark or with only a central light spot; this spot sometimes slightly open caudad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Apex of subgenital plate turned downward away from body . . . . . . . . . . . . . . . . . . I. burksi
Apex of subgenital plate not turned downward away from body . . . . . . . . . . . . . . . . . . . . . 6
6. Light area in ocellar triangle touching pigment of anterior ocellus . . . . . . . . . . . . . I. bilineata
Light arein in ocellar triangle separated from anterior ocellus by a distance at least equal to diameter of ocellus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. namata
7. Subgenital plate triangular, reaching almost to posterior margin of 9th segment . . I. holochora
Subgenital plate rounded, truncate, or notched, reaching halfway or less across 9th segment . 8
8. Subgenital plate truncate; width of base less than half width of 8th abdominal segement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. transmarina
Subgenital plate broadly rounded; width of base more than half width of 8th abdominal segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9. Length to tip o wings less than 8 mm; abdomen uniformy dark on all sides . . . . . . . . . I. nana
Length to tip of wings greater than 8 mm; abdomen variously marked with yellow or orange; if dark dorsally, predominantly yellow ventrally . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. signata
[Home]; [Back to Adult Families]; [Back to Perlodidae Family]
Key to the Adult Isoperla of Ohio