Ephemera ( Ephemera ) sachalinensis Matsumura, 1911

Ephemera ( Ephemera) sachalinensis Matsumura, 1911 View in CoL

Figures 9–15 View FIGURES 9–11 View FIGURES 12–15

Material examined. Russia: Primorsky Krai, Khasansky District, Barabashevka River, below Fish Hatchery , 03.08.2007, 2♀ adults, T. Tiunova; Ryazanovka River , below Okhotbaza, 11.06.2003, 2♀ adults, T. Tiunova; Sakhalinskaya Oblast , Sakhalin Island, Lake Vavayskoye, eastern part, 18.07.2002, 3♀ adults, V. Teslenko; Amurskaya Oblast , Amur River basin, Bureya River, below Kulikovka village , 3♀ adults, T. Tiunova .

Distribution. East Siberia, Far East Russia, Mongolia, Korea, China, Kazakhstan (Irtysh River basin).

The egg has an oval shape close to quadrangular with rounded corners ( Fig. 9 View FIGURES 9–11 ). Dimensions: 204.0–230.0 µm in length (213.5 µm) and 118.0–132.0 µm in width (125.8 µm). The thickness of the extrachorion-adhesive layer is 1.9–3.0 µm ( Fig. 15 View FIGURES 12–15 ). The surface of the adhesive layer is shagreen or roughened ( Fig. 9 View FIGURES 9–11 ). There are one or two micropyles per egg in the equatorial area ( Figs 9 View FIGURES 9–11 , 13 View FIGURES 12–15 ). Micropyles are “tagenoform-type” ( Figs 9–10 View FIGURES 9–11 ), sperm guide weakly expressed (6.4–9.7 µm long, 3.0–5.0 µm wide), almost rectangular, elongated, distal margin not closed ( Figs 10–11 View FIGURES 9–11 ). The micropylar canal, about 5 μm long, does not protrude above the adhesive layer ( Figs 9–10 View FIGURES 9–11 ). Chorionic sculpturing consists of interrupted broken ridges, whose distribution and arrangement extend regularly over the whole chorion surface ( Figs 12–13 View FIGURES 12–15 ). The proximal part of the micropylar opening (MO) does not elevate above the chorion ( Figs 13–14 View FIGURES 12–15 ).