Key to Korean Isometopus species for female

1. Head mostly pale yellowish-brown, posterior margin of head without any dark brown markings....................... 2

- Head mostly dark brown, posterior margin of head with slight pale brown marking, face with sparse punctures and with indistinctly transverse wrinkles...................................................................... I. japonicus

2. Basal part of second antennal segment pale brown; apex of sclerotized ring in female genitalia not curved; northern distribution in Korea, on Quercus and Taxus tree......................................................... .. I. amurensis

- Basal part of second antennal segment dark brown, apex of sclerotized ring in female genitalia sharply projected and slightly curved medially; southern distribution in Korea, on Neolitsea tree................................. I. jejuensis sp. nov.