1. Inner margin of gonostylus with basal or median projection........................................ 2
Inner margin of gonostylus without projection........................................................... 19
2. Inner margin of gonostylus with median projection..................................................... 3
Inner margin of gonostylus with basal projection....................................................... 11
3. Anal point short, not longer than superior volsella....................................................... 4
Anal point relatively long, longer than superior volsella.............................................. 5
4. Superior volsella columniform and straight, anal point rounded at apex........................ ................................................................. C. nigronitens (Edwards, 1929) (Palaearctic)
Superior volsella digitiform and curved, anal point pointed at apex.............................. ......................................................................... C. pflugfelderi Reiss, 1964 (Palaearctic)
5. Anal point with setae in basal half................................................................................ 6
Anal point entirely without setae.................................................................................. 7
6. AR 2.4, superior volsella with 2 apical setae and without lateral setae.......................... ....................................................................... C. usmaensis (Pagast, 1931) (Palaearctic)
AR 1.58, superior volsella with 1 apical seta and 2 lateral setae.................................... .............................................................. C. tobatertius Kikucki & Sasa, 1990 (Oriental)
7. Superior volsella without microtrichia ............... C. emorsus (Townes, 1945) (Nearctic)
Superior volsella with microtrichia............................................................................... 8
8. Anal tergite with high ridge ............................ C. casuarius (Townes, 1945) (Holarctic)
Anal tergite without ridge.............................................................................................. 9
9. Superior volsella distinctly bilobed C. daktylos (Walley in Curran, 1934) (Neotropical)
Superior volsella not bilobed....................................................................................... 10
10. Superior volsella curved, swollen at apex and truncate, anal point tapering to point..... .............................................................................. C. pilicuspis Saether, 1977 (Nearctic)
Superior volsella straight, not swollen at apex, anal point parallelsided to point.......... ..................................................................................... C. parallelus sp. n. (Palaearctic)
11. Tergite IX with pair of dorsal or ventral lobes............................................................ 12
Tergite IX without lobes.............................................................................................. 14
12. Frontal tubercles absent, superior volsella pointed at apex, without microtrichia.......... .......................................................... C. tobasecundus Kikucki & Sasa, 1990 (Oriental)
Frontal tubercles present, superior volsella obtuse at apex, covered by microtrichia. 13
13. Bands of tergite IX joined, superior volsella constricted in middle, widened at apex.... ............................................................................... C. acalcar Reiss, 1990 (Palaearctic)
Bandsoftergite IXseparated,superior volsellaslightly swollen in middle,roundedat apex .................................................... C. mongolkeleus (Sasa & Suzuki, 1997) (Palaearctic)
14. Tergite IX with distinct caudolateral shoulders ... C. darbyi (Sublette, 1960) (Holarctic)
Tergite IX without caudolateral shoulders.................................................................. 15
15. Superior volsella covered by microtrichia.................................................................. 16
Superior volsella without microtrichia........................................................................ 17
16. AR 2.26–2.66, superior volsella twice as wide at base as at middle, gonostylus obtuse at apex ........................................ C. mongoljekeus (Sasa & Suzuki, 1997) (Palaearctic)
AR 3.1–3.5, width of superior volsella at base equal to at middle, gonostylus pointed at apex ..................................................................... C. ariel (Sublette, 1960) (Nearctic)
17. Anal point without lateral setae ........ C. daitogeheus Sasa & Suzuki, 2001 (Palaearctic)
Anal point with lateral setae........................................................................................ 18
18. Gonostylus rounded at apex, superior volsella straight, with apical and lateral setae. LR 1.34–1.44 ................................... C. mongolijeus Sasa & Suzuki, 1997 (Palaearctic)
Gonostyluspointedatapex,superiorvolsellacurved,withapical setaeonly.LR 1.69–1.84 ............................................................................. C. nodus sp. n. (Oriental, Palaearctic)
19. Tergite IX with distinct caudolateral shoulders........................................................... 20
Tergite IX without caudolateral shoulders.................................................................. 21
20. Anal point widest at base, parallelsided, superior volsella not sclerotized.................... .................................................................................. C. lenzi Zorina, 2001 (Palaearctic)
Anal point widest at apex, superior volsella sclerotized................................................. ........................................................................... C. secundus Zorina, 2003 (Palaearctic)
21. Gonostylus apically pointed .................................. C. holsatus Lenz, 1959 (Palaearctic)
Gonostylus apically rounded .............. C. pseudotener (Goetghebuer, 1922) (Holarctic)