12 Isoperlinae species, Klapalek, 1909

Teslenko, Valentina A., 2025, Eggs of twelve Siberian and Far Eastern Isoperlinae (Plecoptera: Perlodidae), Zootaxa 5642 (3), pp. 201-224 : 222-223

Key to the eggs of 12 Isoperlinae species from Siberia and the Russian Far East

1 Egg shape oval with a single concavity; anterior and posterior poles similarly shaped ( Figs. 5 , 14 , 20 , 32 , 59 , 63 )......... 2

- Egg shape pear-shaped or with multiple concave facets; anterior and posterior pole shape asymmetrical ( Figs. 35 , 41 , 48 , 71 , 87 , 90 ).............................................................................................. 7

2 Chorion covered with hexagonal cell impressions and raised or elevated thickened ridges ( Figs. 11 , 18 , 29 , 56 )........... 4

- Chorion covered with hexagonal cell impressions and faintly visible ridges ( Figs. 2 , 64 )............................. 3

3 Chorion covered with shallow pits ( Figs. 7–8 ); collar multi-level with raised longitudinal wavy carinae and small transverse projections ( Figs. 1, 3, 5 ); collar base with a thickened, wavy ridge ( Fig. 3 )................................. I. altaica

- Chorion evenly covered with deep pits ( Figs. 68, 70 ); collar with irregular longitudinal carina transverse projection absent, base of collar embedded, ring short and slightly rough ( Figs. 63, 65 ).......................................... I. obscura

4 Follicle cell impressions visible, walls or ridges thick and raised or elevated and strongly delineated from follicular cell floor ( Figs. 18 , 29 )......................................................................................... 5

- Follicle cell impressions visible, walls or ridges slightly raised or elevated and weakly delineated from follicular cell floor ( Figs. 11 , 56 )......................................................................................... 6

5 Collar with irregular longitudinal ridges and flanged, incised rim ( Fig. 19 ), base of collar surrounded by wide smooth shoulder limited by ring ( Fig. 20 ). Floor of the hexagonal FCIs areas large with numerous (ca. 37–39), shallow, and small pits ( Figs. 22‒23 ). Micropylar row well visible ( Figs. 18, 21 ), micropyles located near paired ridges and surrounded with rosettes ( Figs. 18, 21, 23 ). Micropylar canals tunnel-shaped and long ( Fig. 21 ), orifices set in small oval cup-like depressions with smooth, and open sperm guides extending from cup rims, sperm guides slanted ( Fig. 23 )............................. I. eximia

- Collar with irregular longitudinal ridges extending onto the shoulder; shoulder is contoured with a ring; rim incised and flanged ( Figs. 31–32 ). Floors of the hexagonal FCIs areas small, covered with deep pits (7–13) ( Figs. 33‒34 ). Micropylar row weakly visible ( Figs. 28‒29 ), micropyles located near ridges and surrounded with rosettes of FCI’s ( Fig. 34 ). Micropylar canals smaller than in other species; orifices and sperm guides are weakly visible ( Fig. 34 ).............................. I. flavescens

6 Collar rim flanged and wavy, base of collar deeply embedded and surrounded by a narrow smooth shoulder ( Figs. 56, 58–59 ). Floors in the hexagonal FCIs bear numerous (12–20) deep pits ( Figs. 61‒62 ). Micropylar orifices set in small, oval, cup-like depressions ( Fig. 62 ) and sperm guides tunnel-shaped and wider than ridges ( Fig. 60 ) are associated with follicle cell impressions rosettes ( Fig. 60 )................................................................... I. mongolica

- Collar rim deeply serrated and curved outward ( Fig. 15 ), base surrounded by slightly pronounced shoulder without ring ( Fig. 15 ). Chorion surface is rough with floor of the hexagonal follicular cell impressions with deep groove-like pits (about 11) ( Figs. 16‒17 ). Micropylar canals tunnel-shaped and relatively long; canal seems to float over the orifice and slightly covers it ( Fig. 17 ).......................................................................................... I. asiatica

7 Egg cross-section pentagonal, anterior pole slightly concave, chorion with five longitudinal ridges ( Figs. 85–87 )................................................................................................... I. pseudornata

- Egg cross-section triangular at the posterior pole, chorion with cross-shaped ridges................................. 8

8 Egg cross-section square at the anterior pole, and the anterior pole is convex ( Figs. 38 , 46 ). Collar low ( Fig. 36 , 42 )....... 9

- Egg cross-section square at the anterior pole, anterior pole concave ( Figs. 51 , 78 , 94 ). Collar raised ( Figs. 54 , 75 , 93 )..... 10

9 Collar base bears empty cells of a smoothed triangular shape, directed into the interior of the egg ( Figs. 35–37, 39 ). Chorion surface with hexagonal follicular cell impressions and thick slightly elevated ridges, floors with (ca. 19–29) pits ( Fig. 40 ). Sperm guides short ( Fig. 40 )...................................................................... I. kozlovi

- Collar between longitudinal ridges covered with small pits extending to a narrow and wavy rim ( Figs. 41–44 ). Chorion covered with numerous fine, shallow punctuations and small, donut-shaped rounded knobs, hexagonal follicle cell impressions not visible ( Figs. 45, 47, 41 ). Sperm guides thin, weakly visible ( Fig. 45 )..................................... I. lunigera

10 Chorion covered uniformly and densely with numerous small punctations; hexagonal follicle cell impressions not visible ( Figs 90, 97–98 ). Collar with relatively high irregular longitudinal ridges, base embedded, and covered with pits extending to the rim; rim is flanged and wavy ( Figs. 92–93, 95 ). Anchor small, biscuit-shaped, and flat, covering only the rim of the collar ( Figs. 92–93 ). Micropyles scattered in groups of 3–5 in the subequatorial region ( Figs. 90–91 ); orifices slightly elongated, sperm guides poorly visible ( Figs. 96 ).......................................................... Kazsabia nigricauda

- Egg hexagonal or pentagonal ( Figs. 48 , 72 ). Chorion with hexagonal follicle cell impressions, ridges raised and thickened ( Figs. 55 , 80 ). Collar with irregular longitudinal ridges; rim flanged, serrated, or wavy; collar base offset with pits ( Figs. 54 , 74 ). Anchor mushroom-shaped and covers the collar completely ( Figs. 53 , 73 )....................................... 11

11 Chorion covered with hexagonal follicular cell impressions, floors with pits (about 16) ( Figs. 77, 80 ). Micropyles small and weakly visible, arranged singularly on follicle cell ridges, orifices set in small, oval, cup-shaped depressions, sperm guides poorly visible ( Fig. 77 )........................................................................... I. ornata Chorion covered with hexagonal follicular cell impressions, floors with deep pits (12–20) ( Fig. 55 ). Micropyles small, poorly distinguishable due to their similar size to the pits in hexagonal FCIs, arranged singularly in a row on follicle cell ridges near the anterior ⅓ of the egg ( Figs. 48, 55 ). Orifices round, located on raised horizontal, tunnel-shaped, and relatively long sperm guides laterally; sperm guides weakly visible and unassociated with FCI rosettes ( Figs. 48, 55 )................ I. maculata

Figures

FIGURES 1‒9. Isoperla altaica Šámal, 1939. Russia, Siberia, Krasnoyarsk Krai, Khakassia, Bely Iyus River, Shira Lake basin. Egg. 1. Habitus, cleaned, without anchor, lateral. 2. Habitus with deeply embedded, mushroom-shaped anchor lateral. 3. Collar, longitudinal wavy ridges with small transverse projections, base with wavy ridge, lateral. 4. Anchor with small globular bodies in a peripheral area. 5. Posterior pole, a “multi-level” collar, a view from above. 6. Anterior pole, micropylar row, a view from above. 7. Oval orifices on raised, tunnel-shaped, and long sperm guides. 8. Chorion structure, orifices associated with FCI rosettes. 9. Uncleaned egg, an external membrane with scattered adhesive mushroom bodies.

FIGURES 10‒17. Isoperla asiatica Raušer, 1968. Russia, Far East, Primorsky Krai, Barabashevka River. 10. Habitus, cleaned, with anchor, lateral. 11. Habitus, cleaned, without anchor, lateral. 12. Anchor, mushroom-shaped with globular bodies near the edge, lateral. 13. Collar with irregular longitudinal ridges, lateral. 14. Anterior pole, a view from above. 15. Posterior pole, collar with deeply serrated rim, a view from above. 16. Chorion structure. 17. Micropylar row, canal tunnel-shaped, and long, floating over the orifice and slightly covering it.

FIGURES 18‒23. Isoperla eximia Zapekina-Dulkeit, 1975. Russia, Far East, Jewish Autonomous Region, Kuldur River, Amur R. basin. 18. Habitus, with anchor and micropylar row, lateral. 19. Collar and mushroom-shaped anchor with grouped globular bodies, covered anchor evenly, lateral. 20. Posterior pole, collar with wide smooth shoulder limited by ring, a view from above. 21. Anterior pole, micropylar row, orifices surrounded with rosettes of FCI, view from above and lateral. 22. Chorion structure. 23. Orifices, setting in small oval cup-like depressions with long, smooth, and open sperm guides extending from cup rims, sperm guides slanted, lateral.

FIGURES28–34.Isoperla flavescens Zhiltzova &Potikha,1986.Russia,FarEast, PrimorskyKrai, LazovkaRiver, Partizanskaya R. basin. Egg, cleaned. 28. Habitus, with anchor, lateral. 29. Habitus with collar, micropylar row, and rosettes, lateral. 30. Mushroom-shaped anchor with small globular bodies, lateral. 31. Collar with irregular longitudinal ridges, rim incised, and flanged, lateral. 32. Collar, longitudinal ridges extending onto the shoulder with a ring, view from above. 33. Chorion structure. 34. Orifices and weakly visible sperm guides.

FIGURES 56–62. Isoperla mongolica Zhiltzova, 1972. Russia, West Siberia, Altai Republic, Tuekta River, Ob River basin. Egg. 56. Habitus lateral. 57. Anchor with globular bodies, lateral. 58. Collar, lateral. 59. Posterior pole with collar, view from above. 60. Anterior pole, chorion structure, micropylar row, orifices surrounded by rosettes, lateral. 61. Chorion structure thickened, slightly elevated ridges, and numerous deep pits. 62. Orifices in small, oval, cup-like depressions, sperm guides are tunnel-shaped and wider than ridges.

FIGURES 63–70. Isoperla obscura (Zetterstedt, 1840). Russia, Siberia, Republic of Buryatia, Selenga River, settlement Tataurovo. Egg, cleaned. 63. Habitus, with collar and micropylar row, lateral. 64. Habitus, with anchor, lateral. 65. Collar with rough ring, lateral. 66. Anchor plate, covered with globular bodies, lateral. 67. Micropylar row, lateral. 68. Chorion evenly covered with small and deep pits, lateral. 69. Orifice in oval, cup-like depressions; sperm guides are tunnel-shaped and long. 70. Smooth chorion without punctations around orifice, lateral.

FIGURES 35–40. Isoperla kozlovi Zhiltzova, 1972. Russia, Far East, Amurskaya Oblast, Bureya River, Amur R. basin, Novobureysk settlement. Egg, cleaned. 35. Habitus, with micropylar row, orifices surrounded by rosettes, lateral. 36. Anchor and collar, lateral. 37. Posterior pole with mesh collar, view from above. 38. Anterior pole, convex, view from above. 39. Mesh of the collar, lateral. 40. Orifices in small oval depressions with short sperm guides.

FIGURES 41‒47. Isoperla lunigera (Klapálek, 1923). Russia, Far East, Primorsky Krai, Ussuri River, near Stepanovka village, Amur River basin. Egg. 41. Habitus, lateral. 42. Anchor and collar, lateral. 43. Posterior pole with collar, view from above. 44. Collar, low, with empty pits between low longitudinal ridges, extending to rim. 45. Orifices in small oval depressions and sperm guides. 46. Anterior pole with convex apex, view from above. 47. Chorion structure with shallow punctations and tiny donutshaped rounded knobs.

FIGURES 48–55. Isoperla maculata Zhiltzova, 1977. Russia, Far East, Khabarovsk Krai,Anyuisky National Park,Anyui River, Nilo Chanell, Amur R. basin. Egg. 48. Uncleaned, habitus with anchor, extrachorion layer with mushroom bodies over FCIs, lateral. 49. Cleaned, habitus with collar lateral. 50. Posterior pole, collar rim view from above. 51. Anterior pole with concave apex. 52. Orifice round, lateral. 53. Anchor with globular bodies, lateral. 54. Collar with irregular and raised longitudinal ridges, lateral. 55. Micropyle row on raised, tunnel-shaped, and relatively long and weakly visible sperm guides; chorion structure, and orifices, lateral.

FIGURES 71–80. Isoperla ornata Zhiltzova, 1988. Russia, Far East, Primorsky Krai, Shkotovka River. Egg. 71–72. Habitus, with collar, lateral. 73. Anchor with globular bodies, lateral. 74–75. Collar with irregular and raised longitudinal ridges and a flanged rim, base offset with pits. 76. Orifice in a small, oval, cup-shaped depression; sperm guide is poorly visible. 77. Micropyles row weakly visible, orifices located singularly on follicle cell ridges. 78. Anterior pole with concave apex, view from above. 79. Posterior pole, with collar, view from above. 80. Chorion structure, lateral.

FIGURES 81–89. Isoperla pseudornata Zhiltzova, 1988. Russia, Far East, Primorsky Krai, Ryazanovka River, near the hunting grounds. Egg. 81. Habitus, with anchor and micropylar row, lateral. 82. Habitus, with collar, lateral. 83. Anchor with globular bodies, lateral. 84. Collar with irregular and raised longitudinal ridges and flanged rim. 85. Posterior pole with shallow embedded anchor, view from above. 86. Anterior pole with slightly concave apex, view from above. 87. Posterior pole, with collar, smooth shoulder surrounded with a row of pits, view from above. 88. Chorion structure, lateral. 89. Micropylar row, orifices located on the top of FCI ridges, sperm guides are short and thickened.

FIGURES 90–98. Kaszabia nigricauda (Navás, 1923). Russia, Far East, Amurskaya Oblast, Norsky Nature Reserve, Nora River, cordon near Berezovoye Lake, Selemdzha-Zeya-Amur River basins. Egg. 90–91. Habitus, with collar, cross-shaped ridges, and micropylar row, lateral. 92. Anchor biscuit-shaped, flat, with large, single, globular bodies. 93. Collar covered with pits, extending to the rim, rim flanged and wavy. 94. Anterior pole with slightly concave apex, view from above. 95. Posterior pole with collar, view from above. 96. Orifices slightly elongated, sperm guides poorly visible, lateral. 97–98. Chorion surface uniformly and densely covered with numerous small punctations.