Perlodidae Klapalek 1909

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