Key to males of Microchironomus Kieffer

1. Gonostylus without obvious projection basally ............................................................ 2

­ Gonostylus with distinct projection basally .................................................................. 3

2. Anal point constricted in middle; superior volsella slightly swollen and with 2 or 3 pits at apex .................................................................................... M. cavus sp. n. (Oriental)

­ Anal point nearly parallel sided; superior volsella without pits at apex ......................... .................................................................... M. nigrovittatus (Malloch 1915) (Nearctic)

3. Anal point short, apically expanded; superior volsella with 3–5 long setae and 2–12 short setae subapically ............................................. M. tabarui Sasa 1987 (Palaearctic)

­ Anal point long, parallel sided or expanded in middle; superior volsella with 1–5 long setae and without short setae......................................................................................... 4

4. Anal point with mid ridge bearing lateral setae ............................................................ 5

­ Anal point without mid ridge, but occasionally with tubercle ...................................... 6

5. Superior volsella 3–4 times as long as wide; AR 2.34–2.95 ........................................... ................................... M. deribae (Freeman 1957) (Palaearctic, Afrotropical, Oriental)

­ Superior volsella as long as wide; AR 1.6 ...................................................................... .............................................................. M. trisetifer (Hashimoto et al. 1981) (Oriental)

6. Superior volsella with 1 seta ........ M. fuscitarsus (Guha & Chaudhuri 1979) (Oriental)

­ Superior volsella with 3–5 setae.................................................................................... 7

7. Anal point with tubercle in middle; inner process of gonostylus prominent .................. ........................................................ M. lendli (Kieffer 1918) (Palaearctic, Afrotropical)

­ Anal point with tubercle basal or absent; inner process of gonostylus less prominent. 8

8. Anal point slightly expanded distally, abruptly narrowed near truncate apex ................ .................................................................................. M. teruyai Sasa 1990 (Palaearctic)

­ Anal point parallel sided or slightly expanded in middle, not abruptly narrowed .......... ................... M. tener (Kieffer 1918) (Palaearctic, Afrotropical, Oriental, Australasian)