Key to males of Ablabesmyia Johannsen from Japan

1. Dark macula in middle of cell r4+5 above or proximad to spot in middle of cell m1+2 (Fig. 1); megaseta of gonostylus with expanded apex........................................................................................ 2

- Dark macula in middle of cell r4+5 distad to spot in middle of cell m1+2 (Fig. 52); megaseta of gonostylus with acute apex... 5

2. Wing in distal half with 2 dark spots along costal margin (Fig. 26).................. A. (Ablabesmyia) amamisimplex Sasa

- Wing in distal half with 3 dark spots along costal margin...................................................... 3

3. Aedeagal blade horn-shaped, with slight curve; lateral lobe prominent, almost as long as blade (Fig. 40)............................................................................... A. (Ablabesmyia) jogancornua Sasa et Okazawa

- Aedeagal blade sinuate, with rounded apex; lateral lobe not evident.............................................. 4

4. Aedeagal blade more or less parallel-sided, with apex rounded broadly (Fig. 17)................................................................................................... A. (Ablabesmyia) prorasha Kobayashi et Kubota

- Aedeagal blade tapering to narrow apex (Fig. 3)................................ A. (Ablabesmyia) monilis (Linnaeus)

5. Lateral lobe narrow (Fig. 69)...................................................... A. (Karelia) perexilis n. sp.

- Lateral lobe broad.................................................................................... 6

6. Dorsal lobe with apical brush of setae (Fig. 54).................................... A. (Karelia) makarchenkoi n. sp.

- Dorsal lobe with setal fringe along almost full length (Fig. 66)................................. A. (Karelia) lata n. sp.