1.         Dorsum of terminal segments with a complex of structures including a forked sclerous epiproct             and a dorsal sclerous projection on at least the 8th tergite . . . . . . . . . . . . . . . . . . . . . . .Males

            Dorsum of abdomen without any processes; 8th sternite modified into a simple subgenital plate             of various shapes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Females

Males

2.        Apical segment of upper limb of epiproct long and flat to tip, very thin and regular in                   profile (in lateral view), and with short dorsal retrorse spines. . . . . . . . . . .  Allocapnia recta

            Apical segment of upper limb of epiproct either short, narrow, or tip expanded . . . . . . . . . . . 3

3.         Dorsal process of 8th tergite forming a wide projecton, that is not cleft on meson . A. vivipara

            Dorsal process of 8th tergite cleft on meson, the resultant lobes either close together or far apart             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

4.         Dorsal process of 8th tergite forming a pair of oblique rugose areas, their dorsal aspect U- or V-             shaped. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

            Dorals process forming a transverse bar or oval having 2 or 3 projecting apical points or lobes .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

5.         Profile of dorsal process of 8th tergite fairly long and either declivitous or concave, its anterior             corner angulate; dorsal aspect of dorsal process somewhat U-shaped. . . . . . . . . . . . A. frisoni

            Profile of dorsal process of 8th tergite either much shorter or not declivitous; dorsal aspect of             dorsal process with posterior margin angulate or rounded. . . . . . . . . . . . . . . . . A. granulata

6.         Seventh tergite with a sclerotized process either as large or nearly as large as sclerotized protion             of process of 8th tergite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

            Seventh tergite with no process or wit only a small prcess that is merely a slightly elevated ridge,             or process not sclerous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

7.         Dorsal process of 8th tergite with one mesal and two lateral points . . . . . . . . . . . . . . . . . . . . 8

            Dorsal process with only two lateral points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

8.         Dorsal process of 8th tergite with mesal point as high as, or higher than, lateral points; lower             limb of epiproct with a long, fingerlike tip. . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. indianae

            Dorsal process with mesal point lower than lateral points; lower limb of epiproct tapering evenly             to tip. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A. ohioensis

            Some other combination of these two characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . presumed hybrid of A. indianae x ohioensis

9.         Tergite 8 with a small anterior process in addition to a large, wide incised posterior process . . . .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  A. zola

            Tergite 8 with only a large posterior process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

10.       Membranous apex of upper limb of epiproct merging imperceptibly with more sclerous basal                   portion, its dorsal aspect somewhat bulbous. . . . . . . . . . . . . . . . . . . . . . . . . .  A. illinoensis

            Membranous apex of upper limb of epiproct sharply and angularly delineated at base, its dorsal             aspect short or diamond-shaped. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

11.       Process of 7th tergite situatied at the middle or on the front half of the tergite, viewed from the             side. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. pechumani

            Process of 7th tergite occupying the rear half of the tergite . . . . . . . . . . . . . . . . . . .A. forbesi

12.       Process of 8th tergite with a mesal point at least half the eight of a lateral lobe . . . . . . . . . . .13

            Process either with only two apical lobes or with only a minuter mesal point between them . .14

13.       Profile of dorsal process of 8th tergite as high as wide and without a posterodorsal projecting             corner; lower limb of epiproct wider and extending laterally considerably beyond upper limb, the             lateral margins often angulate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. nivicola

            Profile of dorsal process wider, the posterodorsal corner markedly projecting; lower limb of                   epiproct, extending only slightly beyond sides of upper limb. . . . . . . . . . . . . . . . . . A. smithi

14.       Apical segment of upper limb of epiproct oboid in profile and less than one-half length of base .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A .rickeri

            Apical segment either more slender in profile or more than one-half length of base . . . . . . . .15

15.       Process of 8th tergite with lateral lobes separated by less than half the width of a lobe . . . . . . . .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. mystica

            Process of 8th tergite with lateral lobes much more widely separated . . . . . . . . . . A. pygmaea

Females

1.         Tergite 8 having little or no mesal membranous area, the sclerous portion bridging the entire             segment for half or more of its length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  2

            Tergite 8 having a fairly wide mesal membranous area extending its whole length . . . . . . . . . 3

2.         Sternites 7 & 8 fused, the mesal portion of the fusion forming a solid longitudinal area in which             the intersegmental suture is obliterated. . . . . . . . . . . . . . . . . . . . . . . .  Allocapnia vivipara

            A well-marked intersegmental suture of membranous area across the entire mesal area between             the 7th & 8th sternites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. forbesi

3.         Sternites 7 & 8 solidly fused on meson, the line of fusion either or not visible or indicated by a             dark line or crease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

            Sternites 7 & 8 either completely separated by a membranous area or joined on the meson by             only a faint semisclerous strap; in some instances of the latter, the seventh sternite has an apical             projection extending over the base of the 8th , and in contracted specimens the membrane             cannot be seen without manipulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.         Line of fusion between 7th and 8th sternites not evident on meson,, the two sclerites jointing             without a breatk in profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   A. rickeri

            Line of fusion between 7th and 8th sternites indicated by a dark line and a brak in the profile . . .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5

5.         Apex of 8th sternite with a wide but shallow sagittate mesal protion contrasting sharply with the             much less sclerous remainder of mesal area of the sclerite. . . . . . . . . . . . . . . .  A. illinoensis

            Mesal area of apex of 8th sternite not contrasting noticeably with the more basal portion of the             sclerite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.         Apex of 8th sternite angulate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. zola

            Apex of 8th sternite round or truncate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7.         Sternite 8 produced into a broad rounded flap capable of being reflexed under the edge of the             sternite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

            Sternite 8 with apical flap either indistinct or narrow and truncate . . . . . . . . . . . . . . . . . . . . . 9

8.         Apical flap of 8th sternite projecting markedly beyond mesal edge of lateral humps, which are             chiefly membranous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. pygmaea

            Apical flap shorter, the entire sternite sclerous . . . . . . . . . . . . . . . . . . . . . . . . . .A. ohioensis

9.         Apex of 8th sternite produced inot a truncate flap capable of folding dorsally under the edge of             the sternite; when extended, it reaches considerably beyond the lateral hups of the sternite. . 10

            Apex of 8th sternite not so produced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. indianae

10.       Apical flap of 8th sternite moderately wide, the lateral humps of the sternite chiefly                         membranous, the combination of the two producing a somewhat hourglass-shaped mesal dark             area on the segment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. smithi

            Apical flap of 8th sternite narrower and the lateral humps more extensively sclerotized . . . . . . .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. nivicola

11.       Central portion of 8th sternite forming a flat, sclerous area extending full lengthof sternite and             truncate or nearly so at apex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A. pechamani

            Central portion of 8th sternite with flat area either wedte-shaped, constricted at middle, only             partially sclerous, or only indistinctly differentiated from latera areas except at apex of segment .             . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

12.       Basomesal portion of 8th sternite forming either a nearrow or pale strap joining 7th sternite, the             fusion line only faintly sclerous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. illinoensis

            Sternites 7 and 8 completely separated by membrane; in contracted specimens the membrane             cannot be seen with manipulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13.       Apieomesal portion of 8th sternite differentiated inot a sagittate or emarginated, fluted area set             off laterally by pale membranous areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14

            Apiomesal portion of 8th sternite not markedly differentiatied from lateral areas . . . . . . . . . .15

14.       Apiomesal process of 8th sternit wider, its margin usually truncate or emarginated . . A. frisoni

            Apiomesal process of 8th sternite narrower, usually pointed like a spearhead. . . . A. granulata

15.       Apical margin of 8th sternite usually concave, with or without a projecting, short mesal point or             arcuate lobe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. recta

16.       Apical margin of 8th sternite convex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  A. mystica

           

[Home]; [Back to Adult Families]; [Back to Capniidae Family]

Stoneflies of Ohio

Key to the Adult Allocapnia of Ohio

(Modified from Ross & Ricker, 1971)