Key to adult males of the genus Stempellinella from the Russian Far East and Eastern Siberia

1. Both tibial combs on mid and hind tibia with 1 spur. Median setae weak and short, located close to the anal point (Figs. 5, 40, 45). Median volsella with simple stem, without microtrichia (Figs 7, 40, 46)...................................... 2

- Only one tibial comb on mid and hind tibia with spur. Medial setae strong and long, located far from the anal point (Figs 15, 50). Median volsella with palmate stem or lobe-shaped, with microtrichia (Figs 16, 51)............................. 4

2. AR <0.7. Frontal tubercles small or absent. Median volsella long, S-shaped (Fig. 40).......................................................................................... Stempellinella coronata Inoue, Kawai et Imabayashi

- AR> 0.9. Frontal tubercles well developed, conical. Median volsella curved posterior (Figs 7, 46).................... 3

3. Superior volsella simple, oval form (Fig. 46). Anal tergite with 3–5 small median tergite setae close to anal point (Fig. 45)..................................................................... Stempellinella edwardsi Spies et Saether

- Superior volsella consist of 2–3 lobes bearing medial setae (Figs 6–7). Anal tergite with 6–8 small median setae between anal crests (Fig. 5)............................................................... Stempellinella bazovae sp. nov.

4. Median volsella 35–45 μm long, with palmate stem and 7–10 lamellae (Fig. 51)........ Stempellinella tamaseptima (Sasa)

- Median volsella oval or round shape, 21–30 μm long, with 10–15 small setae (Fig. 16)....... Stempellinella chirka sp. nov.