Key to males of Ainuyusurika Sasa et Shirasaki

1. Superior volsella without lateral and basal setae(Fig. 47F); inner setae of gonostylus short, few and evenly spread, but confined to lower half; wing vein M without seta; LR 1 about 1.3............................................. .................................................................................................................... A. yakucedeum (Sasa et Suzuki)

- Superior volsella with lateral seta, with or without basal seta; inner setae of gonostylus short, numerous, clumped; wing vein M with or without seta; LR 1 0.9–1.2 or about 1.8....................................................... 2

2. Lateral seta of superior volsella at the posterolateral corner of the T-shaped region (Fig. 47E); wing vein M with setae; inner setae of gonostylus numerous, clumped and confined to lower half; LR 1 0.9–1.2....... .......................................................................................................................... A. tuberculatum (Tokunaga)

- Lateral seta of superior volsella situated on the dorsal portion of the shaft (Fig. 47G); wing vein M without setae; inner setae of gonostylus numerous, clumped and evenly distributed; LR 1 about 1.8....................... ...................................................................................................................... A. yakuabeum (Sasa et Suzuki)