Keys to the Isoperla of California (including I. rainiera, I. tilasqua and I. umpqua)

Males

1 Pronotum checkered black on yellow; aedeagus without sclerotized process; paraprocts abruptly tapering to blunt apical tips, usually secondarily barbed ventrally; vesicle a broadly rounded lobe, wider at base then apex (Figs. 11 a-d) ..…... I. pinta

1’ Pronotum without checkered pigment pattern, aedeagus, paraprocts and vesicle variable …..... 2

2 Aedeagus without posterior sclerotized process (Figs. 1, 3, 9-12, 15, 17) ………..……....…………. 3

2’ Aedeagus with variable posterior sclerotized process (Figs. 2, 4-8, 13-14, 16, 18) ………...……. 9

3(2) Vesicle absent or weakly produced (Figs. 9d, 15d).………………...….………….……………… 4

3’ Vesicle present and variably shaped (Figs. 1d, 3d, 10d, 13d, 18d) …………..……..………………….. 5

4(3) Aedeagal posterior margin with a median patch of spinulae (Figs. 15 a-c); apex usually with two small, pointed lobes (Figs. 15 a-c) …………………………………………….. I. sobria

4’ Aedeagal posterobasal margin with a median patch of spinulae concentrated into two distinct longitudinal bands (Figs. 9 a-b); and a second posteroapical patch of spinulae above posterior lobe (Figs. 9a, c) …………………….….. I. miwok

5(3) Ninth tergum with short stout spinulae (sometimes arranged in a bipartite patch) or ninth and tenth terga with distinct patches of long stout setae near posterior margins (Figs. 1c, 10c, 12c) …………………………….…………………....….. 6

5’ Ninth and tenth terga without spinulae, long setae usually scattered ……………...………..….. 8

6(5) Vesicle rounded apically, base broader than apex, occasionally appearing constricted at middle; paraproct length if straightened, subequal to combined length of first two cercal segments, tapering gradually to blunt apices; posterolateral margins of ninth and tenth terga with patches of long stout setae, fewer and smaller on tergum ten (Figs. 12 a-d) ……………...…... I. quinquepunctata

6’ Vesicle truncated or rectangular apically; paraproct length and shape variable; ninth and tenth terga with scattered fine setae, ninth tergum with mesal patches of short stout spinulae (Figs. 1, 10) ………………………………………...…...... 7

7(6) Vesicle rectangular, length half as long as wide (Fig. 1d); apical 1/3 of aedeagus tube-like, directed ventrally, covered with minute spinulae and a posterior pair of finer spinule patches divided or joined apically, apex a complex nipplelike tip (Figs. 1 a-c); paraproct length if straightened greater than combined length of first and second cercal segments, tapering gradually to sharp apices (Fig. 1c) …………………..… I. acula

7’ Vesicle trapezoid shaped, about as long as wide (Fig. 10d); apical 1/2 of aedeagus tube-like, directed posteriorly, covered with minute spinulae and concentrated somewhat above bilobed tip (Figs. 10 a-c); paraproct length if straightened subequal to combined length of first two cercal segments, tapering gradually to blunt apices (Fig. 10c) ..................................... I. mormona

8(5) Abdomen yellow; when everted live and fixed in hot water, aedeagus with one large patch of spinulae concentrated below posterobasal lobe (Fig. 3b), a long thin patch along posteroapical margin (Fig. 3c), apex bulbous, deeply inverted, and without a pair of short apicolateral lobes; when cleared in KOH, apex with a single inverted tube-like process (Fig. 20a), CA-Domingo Spring …………………………...……...…...... I. baumanni

8’ Abdomen dark; when everted live and fixed in hot water, aedeagus with one large patch of spinulae concentrated below posterobasal lobe (Fig. 17b), a long thin patch along posteroapical margin (Fig. 17c), apex bulbous, deeply inverted, and usually with one pair of short sharp apicolateral lobes near apex (similar to I. sobria); when cleared in KOH, apex with two inverted tube-like processes (Fig. 20f), OR, WA …………………………………………... I. tilasqua

9(2) Vesicle a broadly rounded lobe, wider at base then apex (Figs. 6d, 8d, 14d, 16d) …………...…. 10

9’ Vesicle pedunculate, width subequal to length, constricted near base with curved lateral margins, and apex variable (Figs. 2d, 4d, 5d, 7d, 13d, 18d) ……………..………………………………..….… 13

10(9) Aedeagus with at least one patch of stout spinules above sclerotized process (Figs. 6a, 8b, 15a); apex of sclerotized process rounded in lateral view (Figs. 6a, 8a, 15a), distal margin either thin or expanded in posterior view (Figs. 6b, 8b, 15b) ………………………………..………...…..… 11

10’ Aedeagus without a spinule patch above sclerotized process (Fig. 16a); apex of sclerotized process expanded, flattened and projecting dorsally in lateral view (Fig. 16b), bifurcate subapically with two ventrally directed rounded lobes in posterior view (Fig. 16b inset), width of lobes 0.18-0.20 mm …………………..... I. sordida

11(10) A single patch above sclerotized process composed of fine pale spinules; apex of sclerotized process rounded in lateral view (Figs. 8 a-b), distal margin thin and blade-like in posterior view (Fig. 8b) ….…………. I. marmorata

11’ Spinule patch either single or triple and usually dark (Figs. 6c, 14c); apex of expanded sclerotized process rounded in lateral view (Figs. 6a, 14a), distal margin expanded slightly in posterior view (Figs. 6c, 14c) …………………………………..... 12

12(11) A single spinule patch above sclerotized process (Figs. 6a & c) ..…………………… I. fulva

12’ One bi-hemispherical shaped spinule patch above sclerotized process and a pair of smaller rounded patches laterally (Figs. 14 a-c) ……… I. roguensis

13(9) Aedeagal sclerotized process bifurcate in posterior view (Figs. 4-5) …………...…………. 14

13’ Aedeagal sclerotized process not bifurcate in posterior view (Figs. 2, 7, 13, 18) ……………….. 15

14(13) Sclerotized process with long apically pointed bifurcate arms; length of projecting process greater than 0.5 mm (Fig. 4a); abdomen mostly brown ……………………..…………... I. bifurcata

14’ Sclerotized process with short rounded bifurcate lobes; length of projecting process less than 0.5 mm (Figs. 5 a-b); width of bifurcate apicolateral lobes 0.09-0.10 mm; abdomen mostly yellow ………………………………………....... I. denningi

15(13) Posterior margin of aedeagus with elliptical shaped patch of long stout spinulae separated from and above sclerotized process; sclerotized process digitate, with nearly parallel dorsal and ventral margins in lateral view, apex narrowly rounded (Figs. 7 a-c) ..……………….….. I. laucki

15’ Posterior margin of aedeagus without a patch of long stout spinulae; sclerotized process otherwise (Figs. 2, 13, 18) ………….………………...…….... 16

16(15) Sclerotized process crescent shaped in dorsal and ventral views (Figs. 13 b-c); paraprocts gradually tapering to sharp apices (Fig. 13c) OR, WA.………………………….………...…. I. rainiera

16’ Sclerotized process clavate; paraprocts tapering gradually to blunt apices; OR, CA ...….……… 17

17(16) Wings hyaline; aedeagus with one distinct lobe (Fig. 18a); sclerotized process length approximately 0.50 mm (Figs. 18 a-c); mesoposterior area of 8th and 9th terga with bipartite patches of stout spinulae and long fine scattered setae (Fig. 18c), OR ...………... I. umpqua

17’ Wings tinted; aedeagus with four distinct lobes in lateral view (Fig. 2b); sclerotized process length approximately 0.25 mm (Fig. 2b), spinule patches absent on terga 8-9, CA ….…………….. I. adunca

Females

1 Subgenital plate usually with invagination along apical margin (Figs. 19 b-c, 19l-m, 19q-s) .........…. 2

1’ Subgenital plate usually not invaginated (Figs. 19a, 19 d-k, 19n-p) ..…………………………….… 9

2(1) Subgenital plate with deep median invagination, the apex 3–4 times wider than depth (Figs. 19b, 19r) ………………………………........ 3

2’ Subgenital plate with shallow median invagination, the apex 8–10 times wider than depth (Figs. 19c, 19 l-m, 19q, 19s) ..…………….... 4

3(2) Subgenital plate length less than half the width at base (Fig. 19b) …………...…………..… I. adunca

3’ Subgenital plate length approximately half the width at base (Fig. 19r) ………..…….… I. tilasqua

4(2) Subgenital plate apex truncated, with nearly parallel lateral margins (Fig. 19c); deflected ventrally in lateral view, CA-Domingo Spring ……………………………………...…. I. baumanni

4’ Subgenital plate apex rounded and not deflected ventrally in lateral view (Figs. 19 l-m, 19q, 19s) ………………………………………………........... 5

5(4) Subgenital plate width at base approximately half the width of segment 8 and nearly twice that of the subgenital plate length (Fig. 19m) ………………………………...... I. quinquepunctata

5’ Subgenital plate width at base greater than half the width of segment 8 (Figs. 19l, 19q, 19s) …… 6

6(5) Subgenital plate lateral margins broadly rounded (Fig. 19q) ………….…….…… I. sordida

6’ Subgenital plate with short, nearly parallel lateral margins (Figs. 19l, 19s) ………………….…..……. 7

7(6) Pronotum with checkerboard pattern (Fig. 12d inset) …………………………...……………. I. pinta

7’ Pronotum without checkerboard pattern …….... 8

8(7) Apical margin of subgenital plate sometimes invaginated (broadly rounded in Fig. 19j), apex reaches approximately mid-length of ninth sternum (CA) ………………… I. miwok (in part)

8’ Apical margin of subgenital plate typically invaginated (Fig. 19s), apex not reaching midlength of ninth sternum (OR) ………... I. umpqua

9(1) Subgenital plate with lateral margins nearly parallel (Figs. 19j, 19p) ........................................ 10

9’ Subgenital plate with lateral margins not nearly parallel (Figs. 19a, 19 d-i, 19k, 19n-o) ................... 11

10(9) Subgenital plate width nearly as wide as segment 8 (Fig. 19j) …………...…………. I. miwok

10’ Subgenital plate width distinctly less than width of segment 8 (Fig. 19p) ……..……...…… I. sobria

11(9) Subgenital plate triangular (Figs. 19g, 19o) …..………………….. I. fulva, I. roguensis (in part)

11’ Subgenital plate rounded (Figs. 19a, 19 d-g, 19h-i, 19k, 19n) ………….…………………..……….…. 12

12(11) Subgenital plate width at base approximately 4-5 times that of the length (Figs. 19 d-f, 19i, 19n) ………………………………………….……….... 13

12’ Subgenital plate width at base approximately 2-3 times that of the length (Figs. 19a, 19h, 19k) …………………………………………………...... 16

13(12) Subgenital plate completely suffused with dark pigment (Fig. 19n) ………………. I. rainiera

13’ Subgenital plate partially patterned with pigment or completely light (Figs. 19 d-f, 19i) ……….…. 14

14(13) Subgenital plate partially patterned with pigment (Figs. 19d, 19 f-g).…. I. bifurcata, I. fulva

14’ Subgenital plate completely light (Figs. 19e, 19i) …………………………………………………...... 15

15(14) Subgenital plate width at base approximately 3-4 times the length (Fig. 19e) ………… I. denningi

15’ Subgenital plate width at base 6-7 times the length (Fig. 19i) …………………….……… I. marmorata

16(12) Subgenital plate width at base approximately 3 times as wide than length; apex slightly truncated or broadly rounded (Fig. 19k) ...…… I. mormona

16’ Subgenital plate width at base approximately twice that of the length (Figs. 19a, 19h) …..…. 17

17(16) Subgenital plate darkly pigmented (Fig. 19h) ……………………………………..……………. I. laucki

17’ Subgenital plate not darkly pigmented (Fig. 19a) ……………………………………………... I. acula