Key to the Cybocephalidae of Mexico

1. Head extremely short and broad with very short antennae and slightly concave
 clypeus; femora and tibiae of the posterior two pairs of legs extremely dilated and
 laminiform; male with green metallic sheen on head and apical half of pronotum; size
 >1.5 mm...................................................Pycnocephalus metallicus Sharp

1' Head not short, clypeus of normal size and not concave at the apex; only hind
 femora dilated, middle femora and tibiae of the posterior two pairs of legs not or
 only slightly dilated; male without metallic sheen; size <1.5 mm.......................2

2(1') Terminal antennomere of the antennal club rounded (Fig.6-25).............................3

2' Terminal antennomere of the antennal club truncate (Fig. 6-16) or slightly
 em arginate (Fig. 6-6, 6-7) .............................................. ...... .............

3(2') Head and pronotum with a greasy appearance; antennal club small, at most only
 about half the size of the eye........................... Cybocephalus aciculatus Champion

3' Head and pronotum without greasy appearance; antennal club large, about the
 same size as eye; basal plate and median lobe as in Figs. 6-26-6-28 ........................
 ........................................................................... Cybocep halus randalli T R Sm ith

4(2') Terminal antennomere of the antennal club longer than wide (Fig. 6-16); basal
 plate and median lobe as in Figs. 6-17-6-19 ..............Cybocephalus new species 3

4' Terminal antennomere of the antennal club wider than long .............................5

5(4') M ale basal plate emarginate at the apex ....................................... ............... 6

5' M ale basal plate not em arginate at the apex ........................................ ................7

6(5') Terminal antennomere very short and wide (Fig. 6-2); basal plate with very
 shallow emargination at the apex (Fig. 6-5); when viewed laterally the median
 plate on the median lobe only slightly elevated (Fig. 6-4); median lobe as in Fig. 3
 ............................................. ................................... Cybocep halus new species 1

6' Terminal antennomere about as long as wide (Fig. 6-33); basal plate deeply
 emarginate at the apex (Fig. 6-36); when viewed laterally the median plate on the
 median lobe is extremely elevated (Fig. 6-35); median lobe as in Fig. 34................
 ............................................. ................................... Cybocep halus new species 4

7(5') Male basal plate protuberant at the apex (Figs. 6-15, 6-23) .................................8

7' M ale basal plate not protuberant at the apex ........................................ ...............9