Coprinellus is a genus of mushroom-forming fungi in the family Psathyrellaceae. The genus was circumscribed by Petter Karsten in 1879. Most Coprinellus species were transferred from the once large genus Coprinus. Molecular studies published in 2001 redistributed Coprinus species to Psathyrella, or the segregate genera Coprinopsis and Coprinellus. As of January 2016[update], Index Fungorum accepts 62 species of Coprinellus.