Isoperla irregularis (Klapalek, 1923)

Verdone, Chris J. & Kondratieff, Boris, 2016, A New Species Of Isoperla Banks (Plecoptera: Perlodidae) From The Appalachian Mountains, Virginia & West Virginia, U. S. A., Illiesia 12 (13), pp. 74-85 : 83-85

The following couplets to the keys to males, females, and ova are taken directly from Szczytko & Kondratieff (2015). New couplets are given to include the new species .

Males

11 Dorsal head pattern pale, usually without dark brown bands or brown markings connecting ocelli ( Figs. 14.1, 12.1 ) …………………….…… 12

11’Dorsal head pattern with dark brown bands connecting ocelli ( Figs. 17.1 , 20.1 , 33.1) ……... 13

12 Vesicle 3X as long as wide, set in a deep U-shaped depression ¾ as long as length of vesicle ( Fig. 14.2 ); paraprocts lightly sclerotized, bluntly pointed apically, not deflected ventraapically ( Fig. 14.4 ), aedeagus with erect posteromesal sclerotized unicorn-shaped rod ( Figs. 14.6, 14.7 ); head pattern occasionally with thin dark brown bands connecting ocelli distribution–widespread–eastern and midwestern North America ……………………………. I. dicala

12’Not as above …………………………………... 12a

12a Posteromedial sclerotized structure of the aedeagus composed of a thin sclerite bearing 10 short spines and setae ( Figs. 6-8 ); paraprocts broadly triangular extending only slightly over the posterior margin of tergum 10 ( Figs. 3 , 7, 8 ) ………………………………………... I. evanescens

12a’ Posteromedial sclerotized structure lobe-like, deflected ventrally with scattered concentrations of stout sharp spinulae (figs. 12.6, 12.10, 2.11, Szczytko & Kondratieff 2015); paraprocts lightly sclerotized, elongate, sharply pointed apically, extending over ca. ¼-½ length of tergum 10 (figs. 12.3,12.5, Szczytko & Kondratieff 2015) …………………...….. I. decepta

Females

1 Head without a dark pigment pattern, usually without dark brown bands or brown markings connecting ocelli ( Figs. 12.1, 14.1 ) …………….. 2

1’ Dorsal head pattern with discernible dark brown bands connecting ocelli (Figs. 42.1, 6.1)... 3

2 Subgenital plate broadly triangular, extending ½ length of 9 th sternum; usually with posteromedian nipple ( Fig. 14.5 ); distribution– widespread, eastern North America through midwestern US ……………………..……. I. dicala

2’ Subgenital plate evenly rounded to broadly triangular extending over ⅓ or ⅔ length of 9 th sternum (fig. 12.4, Szczytko & Kondratieff 2015; Fig. 9 ) …………………………………………… 2a

2a Subgenital plate evenly rounded extending over ⅓ length of 9 th sternum (fig. 12.4, Szczytko & Kondratieff 2015) ………………………. I. decepta

2a’ Subgenital plate broadly triangular, extending over ⅔ length of 9 th sternum ( Fig. 9 ) ………………………………………... I. evanescens

Eggs

1 Collar absent ( Figs. 12.18 , 22.13, 35.13) ……….. 2

1’ Collar present (Figs. 28.14, 36.9, 41.13, 58.15) …6

2 Chorion covered with raised reticulate thickened ridges, some not connected, eclosion line absent, inter-reticulate punctations absent (figs. 35.13, 35.14 Szczytko & Kondratieff 2015)...... I. nana

2’ Not as above …………………………………… 2a

2a Inter-reticulate punctations present ( Fig. 14 ) ………………………………………... I. evanescens

2a’Chorion without raised reticulate thickened ridges, eclosion line present or absent (figs. 12.18, 22.13, 22.14 Szczytko & Kondratieff 2015) …………………………………………………….. 3

3 Cross section triangular, eclosion line wide, smooth (Figs. 22.13, 22.15) …...……. I. irregularis

3’ Cross section not triangular, either round or concave, eclosion line absent ( Figs. 12.18 , 23.21, 57.15) ……………………………………………... 4

Figures

Fig 20. Type locality. Virginia, Bland Co., Wolf Creek, Grapefield Road.

Figs. 11-14. Isoperla evanescens sp. n. Virginia, Bland Co., Wolf Creek. 11. Ovum. 12. Ovum, showing concave section. 13. Detail of ovum reticulations and punctuations. 14. Detail of ovum chorion and micropyles.

Figs. 16-19. Isoperla evanescens sp. n. Virginia, Smyth Co., North Fork Holston River. 16. Nymphal head, dorsal. 17. Nymphal abdomen, dorsal. 18. Nymphal left lacinia, dorsal: A. submarginal setae. 19. Nymphal left mandible, dorsal: A. dorsal apical tooth and ventral apical tooth.

Figs. 5-8. Isoperla evanescens, sp. n., Virginia, Bland Co., Wolf Creek. 5. Aedeagus, lateral: A. anterodorsal lobe, B. dorsal lobe, C. posterodorsal lobe, D. paired posterolateral lobes, E. posteroventral lobe, F. basal setal band. 6. Aedeagus, posterior. 7. Paraproct, posterior. 8. Posteromedial sclerotized structure of aedeagus with ca. 10 short spines and scallop shaped setae, posterolateral, Isoperla evanescens sp. n., Virginia, Russell Co., Carr Creek.

Figs. 2-4. Isoperla evanescens, sp. n., holotype male. Virginia, Bland Co., Wolf Creek. 2. Head and pronotum, dorsal. 3. Abdomen and paraprocts, dorsal. 4. Abdomen and vesicle, ventral.

Fig. 9. Male paraproct apex, lateral, Isoperla evanescens sp. n. Virginia, Bland Co., Wolf Creek.