| Abstract: | A new riffle beetle species Optioservus gapyeongensis n. sp. is described from the adult and larval stages. Heterlimnius hasegawai (Nomura), previously misidentified in Korea as Optioservus (Cyclolimnius) kubotai Nomura or Optioservus variabilis Nomura, is redescribed. The adults and larvae of both species inhabit attached mosses on substrates of clean mountain streams, headwaters or springs. Photographs of dorsal adults and habitats and line drawings of diagnostic characters are provided. |
