Key to the species of Cysteochila occurring in Japan

The key below is based on the comparison of hundreds of specimens of C. abundantis and the original description (Scott 1874) and photographs of the holotype of C. monstrosa .

1 Median spine on head reaching level far remote from bases of frontal spines; outer margin of paranotum gently curved outward in its entire length; anterior margin of hemelytron nearly straight in its entire length; costal area slightly narrower than subcostal area at widest part.......................................................... C. abundantis Drake & Poor, 1937

- Median spine on head extending beyond bases of frontal spines; outer margin of paranotum nearly straight in its entire length; anterior margin of hemelytron gently curved outward in its entire length; costal area wider than subcostal area at widest part................................................................................ C. monstrosa (Scott, 1874)