Neoperla ussurica Zhiltzova & Sivec, 1996

Figs. 30−34

Material examined. Russia, Far East, Amurskaya Oblast: 1♀, 5 L, Tygda River, 2 km above the mouth, Amur River basin, 13.09.2007, coll. E. Makarchenko; 2♂, Zeya River, 1 km above the bridge near the Krasnoyarovo village, Amur River basin, 20.08.2004, coll. V. Teslenko; Khabarovsk Krai: 7♂, 10♀, Bikin River, Amur River basin, 50 m below the auto bridge, Khabarovsk-Vladivostok highway, 2.07.2005, coll. T. Tiunova; Primorsky Krai: 2♂, 3♀, Ussuri River, 6 km from Stepanovka village, Amur River basin, 26.06.1988, coll. V. Teslenko; 3♂, 4♀, Ussuri River, Stepanovka village, behind the apiary, Amur River basin, 2.07.1987, coll. V. Teslenko; 1♂, 3♀, Ussuri River, near Stepanovka village, Amur River basin, 19.07.1991, coll. V. Teslenko; 1♂, 4♀, the same place, 6.08.2004, coll. V. Lyubaretz; 1♂, 2♀, Chernigovka River, the Gribnoe village vicinities, 24.07.1995, coll. V. Lyubaretz.

Egg. Barrel-shaped (Fig. 30), total length 388−406 μm, equatorial width 198−201 μm (n=4). Anchor umbrella-shaped with a long pedicel (Figs. 30−32); the anchor surface appears with polygonal units, globular bodies mainly single, distributed in the whole surface of the anchor plate but denser located in the peripheral area along the anchor edge (Figs. 31−32). Collar is sessile, wide, rim-flanged, and irregularly incised; collar is margined by two rows of coarse hexagonal and pentagonal-shaped cells (Figs. 30−31). Chorion is covered by numerous straight rows of densely placed punctures between numerous straight bare ribs. The puncture rows converge in groups of three (triplets, sensu Zwick 2023) near the collar and lid. Long and short triplets alternate; the chorion ribs are thicker and raised near the collar and lid; thickened ribs near the collar are smooth (Figs. 30−31, 33). The lid is ringed by irregular rows of distinct deep hexagonal FCIs (ca. 22 visible in the lateral aspect) with fine punctations on the floors; the walls are thick and smooth (Fig. 33). Micropylar row is subequatorial, closer to the anterior pole; each micropyle is located in the median row of a triplet; orifices interrupt the puncture row, and the micropylar canal has a small, semi-oval sperm guide (Figs. 30, 34). The chorionic structure of an external membrane bears scattered globular bodies (Fig. 33).

Comments. The egg of N. ussurica was briefly described and illustrated with a hand-drawn figure in the original description of this species (Sivec & Zhiltzova 1996). The egg size in the original description was slightly larger than the size range given here.

Distribution. East Palaearctic mainland species that is widely distributed in the Amur River basin from Siberia (Transbaikalia) to the Far East, including Amurskaya Oblast, Jewish Avtonomnaya Oblast, south of Khabarovsk Krai, and Primorsky Krai. Neoperla ussurica has also been from South Korea (Stark 2010) and North Korea (Murányi et al. 2015).