Abstract
Collections of Gymnopus sect. Impudicae from the Republic of Korea are evaluated. Three recorded species (G. densilamellatus, G. similis, and G. variicolor) are described as new for the science: Gymnopus densilamellatus is macroscopically characterized as having a brown to reddish brown, sometimes pale ochraceous and later whitish pileus and crowded lamellae. Gymnopus similis has an ochraceous-grey, brownish orange or brownish red pileus, and moderately distant, whitish, later dirty yellowish, greyish, or brownish orange or light brown lamellae. Gymnopus variicolor is characterized by a reddish brown, brownish red or violet brown pileus drying-up to light brown or brown, greyish brown or greyish red, later pale brownish orange lamellae, and greyish brown or greyish red pileus, grey-brown, light to reddish brown in upper part. Gymnopus dysodes is recorded for the first time in Korea. The morphological characteristics of the species are provided with a key for their identification. The taxonomic positions of all taxa are confirmed by the DNA sequences of the internal transcribed spacer region and the large subunit of ribosomal rRNA gene.