Isoperla flavescens Zhiltzova & Potikha, 1986

Teslenko, Valentina A., 2025, Eggs of twelve Siberian and Far Eastern Isoperlinae (Plecoptera: Perlodidae), Zootaxa 5642 (3), pp. 201-224 : 207

Isoperla flavescens Zhiltzova & Potikha, 1986 (in Potikha & Zhiltzova 1986)

Figs. 28–34

Material examined. Russia, Far East, Khabarovsk Krai: 1♂, Anyuisky National Park, Tormasu River, Anyui R. basin, Amur R. basin, 21.06.2018, coll. N. Yavorskaya ; Primorsky Krai: 7♂ 7♀, Lazovka River, Partizanskaya R. basin, below the pass, under the bridge, 13.06.1998, coll. V. Teslenko ; 9♀, Malinovka River, Ussuri R. basin, Amur R. basin, 10 km above the Pozhiga village , highway, 16.06.1998, coll. V. Teslenko .

Egg. The egg of I. flavescens is described here for the first time. Shape oval, symmetrical with anterior and posterior poles broadly rounded ( Figs. 28‒29 ) and a concave cross-section ( Fig. 32 ). Length of 287–302 µm and a width at the equator of 200–217 µm (n=4). Collar well developed, with irregular longitudinal ridges extending onto the shoulder; shoulder contoured with a ring; rim incised and flanged ( Figs. 29, 31–32 ). Anchor mushroom-shaped, with small grouped globular bodies covering the entire surface of the anchor evenly ( Figs. 28, 30 ). FCIs near collar range from pentagonal to hexagonal ( Fig. 32 ). Chorion covered with hexagonal FCIs with thick elevated ridges ( Figs. 28‒29, 32–34 ); floors covered with deep pits, their number not exceeding 9–13 ( Figs. 33‒34 ). Micropylar row visible near anterior ¼ ( Fig. 29 ). Micropyles located near ridges and surrounded with rosettes of FCIs ( Figs. 29, 34 ). Micropylar canals smaller than in other species; orifices and sperm guides weakly visible ( Fig. 34 ).

Distribution. East Asian species with limited distribution in the south of the Russian Far East (Jewish Autonomous Region, Khabarovsk Krai, and Primorsky Krai). South Korea ( Kim et al. 1998). China (Changbai Mountains) ( Huo et al. 2022).

Figures

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.