Key to the genera of Troctopsocidae

1. Head somewhat flattened, with vertex nearly sharp-edged. Sc in forewing joining R1... Selenopsocus Lienhard & Mockford

-. Head normal. Sc in forewing ending in R stem, costa, or membrane.............................................. 2

2. First segment of Rs in hindwing present. Pretarsal claws: anterior claw of each foot foliose, setose, terminating in a hook; posterior claw slender, curved, untoothed, bearing a long basal seta bent at its apex (see Mockford 1967, Figs 50, 51)......... 3

-. First segment of Rs in hindwing absent. Pretarsal claws not as above, the two claws of each foot equal.................. 4

3. In forewing, Cu loop joined to vein M3 by a crossvein. T-shaped sclerite present................. Troctopsocus Mockford

-. In forewing, Cu loop free. T-shaped sclerite absent..................................... .. Troctopsocopsis Mockford

4. Forewings markings consisting of broad banding or forewings elytriform (females of Coleotroctellus Lienhard), in some cases uniformly dark in color. In hindwing, vein R4+5 directed distally................................................ 5

-. Forewings markings consisting of scattered small spots (Figs 1, 11). In hindwing, vein R 4+5 directed postero˗distally (Figs 2, 12)............................................................................... Troctopsocoides n.gen.

5. Antennae 13-segmented. Female forewings elytriform, those of male normal................... Coleotroctellus Lienhard

-. Antennae 11-segmented. Forewings of both sexes not elytriform................................................ 6

6. First antennal flagellomere longer than second and third together. Female subgenital plate with four stout setae at apex............................................................................... Thaipsocus Lienhard & Mockford

-. First antennal flagellomere approximately equal to second in length. Female subgenital plate without stout setae at apex..................................................................................... Troctopsoculus Mockford