159 

 Jewett: Plecoptera 



17 



18 



19 



20 



21 



junction with cu-a and then curved outwardly again 



(fig. 6:7e) Capnia Pictet 184 1 



R, of fore wing not bent abruptly upward at its origin; 

 first anal vein of fore wing without an abrupt bend at 



its junction with cu-a (fig. 6:7c, f-h) 10 



Sc ending much before the cord (fig. 6:7/); supra-anal 

 process of male genitalia double; east of Rocky Moun- 

 tains Allocapnia Claassen 1928 



Sc ending at or beyond the cord (fig. 6:7c,; g, h); supra- 

 anal process of male genitalia never double 11 



First anal vein of fore wing slightly bent beyond cu-a 

 (fig. 6:7^); base of male 9th sternite without a lobe; 



east of Rocky Mountains Nemocapnia Banks 1938 



First anal vein of fore wing without a bend beyond 



cu-a (fig. 6:7c,A) 12 



Base of male 9th sternite without a lobe; eastern 



North America Paracapnia Hanson 1946 



Base of male 9th sternite with a lobe 13 



Cerci with fewer than 11 segments; 1 cross vein in 

 costal area beyond the cord (f g. 6:7 h); western North 



America Eucapnopsis Okamoto 1922 



Cerci with more than 11 segments; 2 or more cross 

 veins in costal area beyond the cord (fig. 6:7c); western 



North America Isocapnia Banks 1938 



Coxae without membranous areas on ventral surfaces; 

 male cerci with at least 3 segments; female 9th sternite 



with a long projection Brachyptera Newport 1851 



Coxae with small round membranous areas on ventral 

 surfaces; male cerci 1-segmented; female 9th sternite 

 without a long projection. . . . .Taeniopteryx Pictet 1841 

 Ventral abdominal gills on segment 3; western North 



America Pteronarcella Banks 1900 



No ventral abdominal gills on segment 3 



Pteronarcys Newman 1838 



Branched gills absent from the thorax; cubitoanal cross 

 vein, if present, usually distant from the anal cell by 

 more than its own length (figs. %:li,k,l; 6:9a-c) .... 17 

 Profusely branched gills at the lower angles of the 

 thorax; cubitoanal cross vein of fore wing usually 

 either in the anal cell or distant from it by no more 

 than its own length (figs. 6:7^; 6:lla-c) 



PERLIDAE 28 



Pronotum nearly rectangular, the corners acute or 

 narrowly rounded'; fork of 2nd anal vein of the fore 

 wing included in the anal cell so that its 2 branches 

 leave the cells separately (fig. 6:7i,l) 



PERLODTDAE 18 



Pronotum ellipsoidal; 2nd anal vein of the fore wing 

 either not forked or forked beyond the anal cell except 

 in Kathroperla which has the fork at the margin of the 

 cell or included in it (figs. 6:1k; 6:9a-c) 



CHLOROPERLIDAE 23 



Male 10th tergite completely cleft; supra-anal process 

 of male genitalia broadly and irregularly U-shaped in 

 side view, attached to the anterior dorsal end of the 

 segment, surrounded by a fleshy cowl which is slit 

 dorsally, and usually with 2 lateral stylets inserted 



on it ISOGENINAE 19 



Male 10th tergite entire, or at most slightly notched; 



supra-anal process of male simple 20 



Wings with 4 to many cross veins beyond the cord, and 

 these usually arranged in an irregular network (fig. 

 6:7Z); 7th abdominal sternite of male without a lobe 



Arcynopteryx Klapalek 1904 



Wings normally with no more than 2 cross veins beyond 

 the cord (fig. 6:7i); 7th abdominal sternite of male 

 usually with a lobe behind .... Isogenus Newman 1833 

 Male subanal lobes produced inward and backward, 

 meeting along their inner face (fig. 6:40a); no lobe on 

 the 8th sternite of male 



PERLODINAE Diura Billberg 1820 



Male subanal lobe not as above — either little modified 

 or produced into erect or recurved hooks (fig. 6:86); 

 usually a lobe at the hind margin of the male 8th 



sternite (sometimes obsolescent) (fig. 6:8a) 



ISOPERLINAE 21 



Subanal lobes of male not formed into hooks; male 10th 





Fig. 6:8. Male terminalia of /soper/o potricia. a, ventral 

 view; b, dorsal (Frison, 1942b). 



tergite slightly notched dorsally; Oregon and California 

 Calliperla Banks 1947 



— Subanal lobes of male produced into erect or recurved 

 hooks (fig. 6:86); male 10th tergite entire 22 



22. Male with lobe on hind margin of 8th sternite 



Isoperla Banks 1906 



— Male without lobe on hind margin of 8th sternite but a 

 lobe on the 7th sternite; Oregon . . .Rickera Jewett 1954 



23. Eyes set far forward except in Utaperla; body narrow 

 and elongate; anal area of hind wing of normal size; 

 anal veins with 5 to 7 branches reaching the margin of 

 the wing (fig. 6:96) PARAPERLINAE 24 



— Eyes normally situated; body less elongate; anal area 

 of hind wing often reduced or even absent; anal veins 

 with 4 branches at most (figs. 6:1k; 6:9a,c) 



CHLOROPERLINAE 26 



24. Head longer than wide; western North America 



Kathroperla Banks 1920 



— Head about as wide as long 25 



25. Ocellar area dark; at least 3 cross veins in costal area 

 beyond the subcosta; posterior margin of the male 7th 

 sternite not raised and hairy; western North America 



Paraperla Banks 1906 



— Ocellar area light; fewer than 3 costal cross veins 

 beyond the subcosta; posterior margin of male 7th 

 sternite raised and hairy; western North America 



Utaperla Ricker 1952 



26. Anal area of hind wing absent (fig. 6:9c) 



Hastaperla Ricker 1935 



— Anal area of hind wing present (figs. 6:1k; 6:9a) ... 27 



27. Third anal vein of fore wing with basal part fused with 

 2nd anal vein so that 2nd anal vein appears branched 

 (fig. 6:7A;) Mloperla Banks 1906 



— Third anal vein of fore wing not present, or if present, 

 not fused with 2nd anal vein so that 2nd anal vein 

 appears branched (fig. 6:9a); east of Rocky Mountains 



Chloroperla Newman 1836 



28. Males with subanal lobes produced inward and upward, 

 sharply pointed or hooked (fig. 6:10a); middle of the 

 hind margin of the 10th tergite not cleft; a definitely 

 raised knob or "hammer" present on the 9th sternite, 

 except in Perlesta; dorsal prolongations of the hind 

 margin of the 10th tergite usually present in Claassenia 

 where they are developed from the lateral angles rather 

 than from the sides of a median cleft 



ACRONE URIN AE 29 



— Subanal lobes of male not modified as above; hind 

 margin of the 10th tergite deeply cleft at the middle 

 and with dorsal prolongations developed from the sides 

 of the cleft and adjacent parts of the hind margin (fig. 

 6:10c); no hammer on the 9th sternite . . . PERLINAE 34 



29. With 2 ocelli 30 



— With 3 ocelli 31 



30. Several costal cross veins before the end of the sub- 

 costa; course of the 2nd anal vein sinuate (fig. 6:11a); 

 south of U. S. border; one record from Texas 



Anacroneuria Klapalek 1909 



— Usually no costal cross veins before the end of the 

 subcosta; course of 2nd anal vein not sinuate (fig. 



