Isoperla lunigera

Isoperla lunigera (Klapálek, 1923) Figs. 41–47 Material examined. Russia, Far East, Amurskaya Oblast: 1♂ 2♀, Dikan River, Bureya R. basin, Amur R. basin, 1 km below auto bridge, 5 km from Novobureisk settlement, 10.07.2015, coll. T. Tiunova; Khabarovsk Krai: 1♂, Komsomolsk Nature Reserve, Bitki River, Udyl Lake, 13.07.2021, coll. N. Yavorskaya; Jewish Autonomous Region: 1♀, Bastak Nature Reserve, Scorpion’s Lair Stream, 29.07.2022, coll. T. Vshivkova; Primorsky Krai: 4♂ 3♀, Ussuri River, Amur R. basin, Stepanovka village, 26.06.1988, coll. V. Teslenko; 3♂ 4♀, Ussuri River, Kamenka village, 5.07.1993, coll. V. Teslenko; 1♂ 9♀, Shumnaya River, Ussuri R. basin, Shumny settlement, 29.06.2017, coll. V. Lyubarets. Egg. Rhombus-shaped, tapered toward the anterior and posterior poles; cross-shaped ridge present medially; posterior pole triangular in cross-section, with a distinct cross-shaped ridge on each side; anterior pole is quadrangular with four longitudinal ridges; anterior apex is convex (Figs. 41, 43, 46). Length 217–236 µm, maximum width medially 174–182 µm (n=2). Collar low, longitudinal ridges short, their bases well visible dorsally (Figs. 42–44); collar sides between ridges covered with empty pits extending to rim, rim narrow and slightly wavy apically (Figs. 42, 44). Anchor mushroom-shaped and covered with globular bodies scattered in groups of 2 or 3, globular bodies larger than other species (Fig. 42). Chorionic surface covered with numerous, very shallow punctuations; hexagonal FCIs not visible, eclosion line absent (Figs. 44–45, 47). In addition to shallow punctations, there are small and tiny donut-shaped rounded knobs present on the chorion surface (Figs. 45, 47). Micropyles are positioned singularly or in a row of 3 near the anterior ⅓ of the egg (Fig. 41); orifices set in small oval cup-like depressions, and sperm guides are long and thin, weakly visible (Fig. 45). Distribution. East Palaearctic species. Russia, Siberia: Altai, Sayan, Baikal Lake basin, Transbaikalia; Far East: Amurskaya Oblast, Jewish Autonomous Region, Khabarovsk Region, Primorsky Krai. East Kazakhstan (Devyatkov 2022). Mongolia. China (Zhu et al. 2007). Remarks. In addition to the dimensions and characteristics of the chorion structure, the original description of the collar by Zwick & Surenkhorloo (2005) generally corresponds to the results obtained here by SEM.