Ephemera (Ephemera) sachalinensis Matsumura 1911

Ephemera (Ephemera) sachalinensis Matsumura, 1911

Figures 9–15

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). 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). The surface of the adhesive layer is shagreen or roughened (Fig. 9). There are one or two micropyles per egg in the equatorial area (Figs 9, 13). Micropyles are “tagenoform-type” (Figs 9–10), 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). The micropylar canal, about 5 μm long, does not protrude above the adhesive layer (Figs 9–10). Chorionic sculpturing consists of interrupted broken ridges, whose distribution and arrangement extend regularly over the whole chorion surface (Figs 12–13). The proximal part of the micropylar opening (MO) does not elevate above the chorion (Figs 13–14).