What is now recognized as a single morphologically variable taxon named "Galerina marginata" was once split into five distinct species. Norwegian mycologist Gro Gulden and colleagues concluded that all five represented the same species after comparing the DNA sequences of the internal transcribed spacer region of ribosomal DNA for various North American and European specimens in "Galerina" section "Naucoriopsis". The results showed no genetic differences between "G. marginata" and "G. autumnalis", "G. oregonensis", "G. unicolor", and "G. venenata", thus reducing all these names to synonymy. The oldest of these names are "Agaricus marginatus", described by August Batsch in 1789, and "Agaricus unicolor", described by Martin Vahl in 1792. "Agaricus autumnalis" was described by Charles Horton Peck in 1873, and later moved to "Galerina" by A. H. Smith and Rolf Singer in their 1962 worldwide monograph on that genus. In the same publication they also introduced the "G. autumnalis" varieties "robusta" and "angusticystis". Another of the synonymous species, "G. oregonensis", was first described in that monograph. "Galerina venenata" was first identified as a species by Smith in 1953. Since "Agaricus marginatus" is the oldest validly published name, it has priority according to the rules of botanical nomenclature.