Key to New World Schizopteridae

1 Forewing with four closed submarginal cells (Fig. 1A, black arrows); eyes relatively large, head wider than prothorax (Fig. 1A); labium four-segmented; male sternum VIII well-developed; ovipositor well-developed............................. Hypselosomatinae ( Williamsocoris Carpintero and Dellapé, Glyptocombus Heidemann, Ommatides Uhler, Hypselosomops Hoey-Chamberlain and Weirauch, Hypsohapsis Hoey-Chamberlain and Weirauch)

- Forewing with less than four closed submarginal cells (Fig. 1B, black arrows); eyes smaller, head not noticeably wider than prothorax (Fig. 1B); labium three- or four-segmented; male sternum VIII reduced, fused with pygophore; ovipositor welldeveloped or obsolete................................................................................. 2

2 Labium four-segmented (Fig. 1C)........................................................................ 3

- Labium three-segmented (Fig. 1D)...................................................................... 6

3 The basal half of the forewing with a deep costal fracture (Fig. 1E, black arrow)............................................................................................ Guapinannus Wygodzinsky and Tropistotrochus Reuter

- The basal half of the forewing without a deep costal fracture (Fig. 1B, F, K)...................................... 4

4 Eyes large, about 2/3 as wide as synthlipsis; basal cell of the forewing much smaller than trapezoidal cell, or if larger then only three veins excluding claval veins emanate from trapezoidal cell; veins are often traced by areoles (Fig. 1F); tarsal formula 2- 2-3 in both sexes.............................................................. Peloridinannus Wygodzinsky

- Eyes small, about 1/3 or less as wide as synthlipsis; basal cell of the forewing larger or equal to trapezoidal cell; four to five veins excluding claval veins emanate from trapezoidal cell; veins are not traced by areoles; tarsal formula different...... 5

5 Labium straight and long, extending beyond hind coxa (Fig. 1G, black arrow); tarsal formula 3-3- 2 in males, 2-2- 2 in females; body size <1.3 mm; ovipositor vestigial............................................... Chinannus Wygodzinsky

- Labium short, not surpassing middle coxa (Fig. 2F); tarsal formula 3-3- 3 in males, 2- 2-3 in females; total size> 2 mm; ovipositor well-developed (Fig. 9B)........................................................... Meganannus, n. gen.

6 Labium truncated (Fig. 1D, white arrow); pronotal collar absent (Fig. 1I, white arrow)..................................... Corixidea genus group ( Corixidea Reuter, Hoplonannus McAtee and Malloch, Membracioides McAtee and Malloch, Oncerodes Uhler, Voccoroda Wygodzinsky, Voragocoris Weirauch)

- Labium tapering (Fig. 1C, white arrow; 1G, black arrow); pronotal collar usually present (Fig. 1K, grey arrow).......... 7

7 Cu-vein on male forewing thickened and darkened (see Fig. 44 in Wygodzinsky 1948); macropterous, 1AN vein on forewing merges with Cu distally; right side of the male sternum IV with a hook..................... Itagunannus Wygodzinsky

- Cu-vein on male forewing not thickened and darkened; in macropterous specimens 1AN disappearing before reaching any other vein or forewing margin (Fig. 1B, white arrow); right side of male sternum IV without a hook................... 8

8 Posterolateral spine on metepisternum well developed (Fig. 1H, white arrow); radial (= posterior costal) cell pentagonal or quadrate (Fig. 1B, grey arrow), considerably smaller than anterior costal cell, distal R-vein straight......................

. the Schizoptera genus group ( Ceratocomboides McAtee and Malloch, Ptenidiophyes Reuter, Schizoptera Fieber, Orthorhagus McAtee and Malloch, Kophaegis McAtee and Malloch) - Posterolateral spine on metepisternum absent (Fig. 1K, white arrow); radial (= posterior costal) cell elongate (Fig. 1J, black arrow), slightly smaller than anterior costal cell, distal part of R-vein curved...................................... 9

9 Head moderately to greatly elongated (Fig. 1K), but without frontal projection; labium very slender, curved dorsad at apex, second labial segment much longer than first and third combined (Fig. 1K, black arrow); basal and discoidal cells separate (Fig. 1J, grey arrows).......................................... Nannocoris Reuter and Soekhnandanius Makhan

- Head not elongated, but with a frontal projection bearing three stout setae (see Fig. 2 in: Wygodzinsky 1947); labium moderately slender, not curved dorsad at apex, second labial segment roughly as long as either first or third; basal and discoidal cells merged (see Fig. 1 in: Wygodzinsky 1947)........................................... Biturunannus Wygodzinsky