Isoperla kozlovi Zhiltzova, 1972

Teslenko, Valentina A., 2025, Eggs of twelve Siberian and Far Eastern Isoperlinae (Plecoptera: Perlodidae), Zootaxa 5642 (3), pp. 201-224 : 209

Isoperla kozlovi Zhiltzova, 1972

Figs. 35–40

Material examined. Russia, Far East, Amurskaya Oblast: 5♂ 15♀, Bureya River, Amur R. basin, Novobureysk settlement, 27.06.2013, coll. V. Teslenko ; 16♂ 19♀, Bureya River, Novobureysk settlement, above Podoshva island , 28.06.2013, coll. V. Teslenko ; Khabarovsk Krai : 10♂ 17♀, Bikin River, Amur R. basin, 300 m below the bridge, Vladivostok-Khabarovsk highway, 18.06.2000, coll. T. Tiunova ; Prymorsky Krai: 1♂, Razdolnaya River, Zagorodnoye settlement, 08.06.2019, coll. E. Gorovaya.

Egg. Rhombus-shaped, uniformly tapered toward the anterior and posterior poles, with a cross-shaped ridge along the anterior ⅓; posterior pole cross-section triangular, with three distinct longitudinal ridges; anterior pole quadrangular with four longitudinal ridges; anterior end of egg is convex ( Figs. 35, 37, 38 ). Length 269–290 µm, width widest at ⅓ from the anterior pole of 173–177 µm, thickness 2.4 μm (n=2). Collar well developed, with short longitudinal ridges and a narrow flanged and slightly wavy rim; base covered with a mesh of empty cells of a smoothed triangular shape directed into interior of egg ( Figs. 36–37, 39 ). Anchor mushroom-shaped, covered with small, globular bodies larger than other species ( Fig. 36 ). Chorion near collar smooth, ranging downward from pentagonal to hexagonal FCIs with thick and elevated ridges; floors flat with numerous (ca. 19–29) punctations ( Figs. 37‒38 ). Eclosion line absent. Micropylar row visible near the anterior ⅓ of egg ( Fig. 35 ). Micropyles scattered in groups of 3 on FCI ridges and surrounded by rosettes of FCIs; orifices set in small oval cup-like depressions with short sperm guides ( Fig. 40 ).

Distribution. East Palaearctic species. Russia, West Siberia, West Altai, Sayan, Baikal Lake basin, Transbaikalia; Far East: Amurskaya Oblast, Jewish Autonomous Region, Khabarovsk Region, Primorsky Krai. East Kazakhstan ( Devyatkov 2022). Mongolia. China, Northeast, including Changbai Mountain, Jilin Province ( Chen et al. 2021). South Korea ( Hwang & Muranyi 2020).

Remarks. The original description of the egg indicates one of the diagnostic features—the shape of the collar. Collar with a few subdued meshes, edge simple, base smoothly bulging into interior of egg ( Zwick & Surenkhorloo 2005).

Figures

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.