Basionym:
Agaricus horizontalis Bull., Herbier de la France 7: t. 324 (1787) [MB#169968]
Obligate synonyms:
- Psilocybe horizontalis (Bull.) Vellinga & Noordel., Persoonia 16 (1): 128 (1995) [MB#414021]
- Melanotus horizontalis (Bull.) P.D. Orton, Notes from the Royal Botanical Garden Edinburgh 41: 595 (1984) [MB#107639]
- Naucoria horizontalis (Bull.) Sacc., Mémoires de la Société d'Émulation de Montbéliard 5: 347 (1873) [MB#244615]
- Phaeomarasmius horizontalis (Bull.) Kühner, Encyclopédie Mycologique 7: 33 (1935) [MB#463660]
- Agaricus fallax J.F. Gmel., Systema Naturae 2 (2): 1411 (1792) [MB#490188]
- Hylophila horizontalis (Bull.) Quél., Enchiridion Fungorum in Europa media et praesertim in Gallia Vigentium: 104 (1886) [MB#802762]
- Derminus horizontalis (Bull.) J. Schröt., Kryptogamen-Flora von Schlesien 3-1(5): 581 (1889) [MB#623933]
Taxonomic synonyms:
Melanotus textilis Redhead & Kroeger, Mycologia 76: 868 (1984) [MB#106261]