The genus was circumscribed by the Finnish mycologist Petter Adolf Karsten in 1879.

Molecular studies published in 2001 redistributed Coprinus species to Psathyrella, or the segregate genera Coprinopsis and Coprinellus.

[2] In 2020 Phylogenetic analysis conducted by the German mycologists Dieter Wächter & Andreas Melzer reclassified many Coprinellus species as belonging to the new genus Tulosesus.

[3][4] As of July 2022[update], Index Fungorum accepted 62 species of Coprinellus.

Many of these species appear similar and require microscopic analysis to differentiate and identify.