Project description:A new species of Hydnum subgenus Rufescentia is described based on collections made in Canada (New Brunswick, Newfoundland and Labrador) and the USA (New York). The new species is found in conifer dominated forests (e.g. Abies, Picea) and occurs in bryophyte-covered (Sphagnum, Bazzania) soil. It differs from the ecologically similar H. quebecense in the duller brown colors of the basidiomes, the smaller basidiospores and the basidia predominantly with three or four sterigmata. Phylogenetic analysis of the ITS region place H. subconnatum and H. oregonense as the closest relatives of H. atlanticum, but these taxa differ in the larger basidiospores, number of sterigmata per basidium, caespitose growth and/or geographic distribution. Citation: Justo A, Hood AW, Swenie RA, Matheny PB (2023). Hydnum atlanticum, a new species from Eastern North America. Fungal Systematics and Evolution 11: 63-70. doi: 10.3114/fuse.2023.11.05.