Key to the Korean species of Philhygra

1. Pronotal pubescence in midline directed anteriorly in apical half and posteriorly in basal half (Fig. 7 B); a-sensillum of labrum short (Fig. 6 B); prementum with medial pseudopores present................................................. 2

- Pronotal pubescence in midline directed anteriorly (Fig. 8 B); a-sensillum of labrum relatively long (Fig. 4 B); prementum with medial pseudopores absent.............................................................................. 3

2. Tergite VIII with 5 macrosetae on each side of midline (Fig. 6 D); male sternite VIII with 12 macrosetae on each side of midline (Fig. 6 E)..................................................................... P. pseudoelongatula

- Tergite VIII with 4 macrosetae on each side of midline (Fig. 7 D); male sternite VIII with 8 macrosetae on each side of midline (Fig. 7 E)...................................................................................... P. sparsa

3. Antennomeres 8–10 slightly elongate; tergite VIII with more than 5 macrosetae on each side of midline............... 4

- Antennomeres 8–10 about as long as wide or slightly transverse; tergite VIII with 4 macrosetae on each side of midline... 5

4. Body length less than 4.0 mm (Fig. 1 A); tergite VIII with 5 macrosetae on each side of midline; posterior margin of male sternite VIII broadly round.................................................................... P. elongatula

- Body length more than 4.0 mm (Fig. 1 D); tergite VIII with 7 macrosetae on each side of midline; posterior margin of male sternite VIII subtruncate......................................................................... P. polaris

5. Body relatively robust (Fig. 1 B); mesoventral process distinctly pointed at apex (Fig. 3 B); female sternite VIII with short marginal setae (Fig. 3 D).................................................................... P. homoeopyga

- Body relatively narrow in dorsal aspect (Figs. 1 C, 1G); mesoventral process pointed or slightly pointed at apex (Fig. 4 C); female sternite VIII with moderately long marginal setae...................................................... 6

6. Head about as wide as long; posterior margin of tergite VIII emarginate (Fig. 4 D); posterior margin of male sternite VIII with conspicuously long marginal setae (Fig. 4 E); posterior margin of female sternite VIII convex, more or less round..................................................................................................... P. palustris

- Head slightly longer than wide; posterior margin of tergite VIII truncate (Fig. 8 D); posterior margin of male sternite VIII with moderately long marginal setae; posterior margin of female sternite VIII subtruncate.................... P. yokkaichiana