The morphology and infraciliature of a new ciliate, Cyrtohymena seorakensis sp. n., discovered in a moss sample from South Korea, were investigated. The new species is distinguished from congeners by having rather fewer, randomly scattered, yellowish cortical granules, 23-30 adoral membranelles, invariably four transverse cirri in morphostatic specimens, and a total of 62 dorsal bristles on average. Phylogenetic analysis based on 18S rDNA sequences showed that the new species clusters with an Indian population of C. citrina.
Keywords: Protozoa, Korea, morphology, ontogenesis, SSU rDNA, terrestrial ciliates.