(1978) Leucocoprinus cygneus is a species of mushroom producing fungus in the family Agaricaceae.

[4] In 1978 the Belgian mycologist Paul Heinemann created the new genus Sericeomyces in an attempt to better arrange the species which are now recognised as belonging to the Lepiota, Leucoagaricus and Leucocoprinus genera.

He reclassified this species as Sericeomyces cygneus but noted that placing it in this newly created genus was questionable.

[5] This proposed placement turned out to be short lived as it was also in 1978 that Austrian mycologist Meinhard Michael Moser classified it as Cystolepiota cygnea[6] and the French mycologist Marcel Bon classified it as Leucocoprinus cygneus, which was ultimately the classification which was adopted.

[3][7] The specific epithet cygneus (originally cygnea) derives from the Latin for cygnus meaning swan.