Obligate Synonyme: Leccinum aurantiacum subsp. duriusculum (Schulzer ex Kalchbr.) Hlavácek, Mykologický Sborník 34 (3-6): 64 (1958) [MB349688] Krombholziella duriuscula (Schulzer ex Kalchbr.) Imler, Bulletin Trimestriel de la Société Mycologique de France 54 (1): 61 (1938) [MB462212] Krombholzia aurantiaca f. duruiscula (Schulzer ex Kalchbr.) Vassilkov (1956) [MB346964] Krombholzia aurantiaca subsp. duriuscula (Schulzer ex Kalchbr.) Maire, Publicaciones del Junta de Ciencias Naturales Barcelona Sèr. Botànica. 15 (2): 43 (1933) [MB257840] Krombholzia aurantiaca f. duriuscula (Schulzer ex Kalchbr.) Vassilkov, Botanicheskie Materialy Otdela Sporovyh Rastenii Botanicheskogo Instituta Imeni V. L. Komarova Akademii Nauk SSSR 11: 138 (1956) [MB536809] Gyroporus rufus var. duriusculus (Schulzer ex Kalchbr.) Quél., Enchiridion Fungorum in Europa media et praesertim in Gallia Vigentium: 161 (1886) [MB802863] Suillus duriusculus (Schulzer ex Kalchbr.) Kuntze, Revisio generum plantarum 3 (3): 535 (1898) [MB586182] Gyroporus duriusculus (Schulzer ex Kalchbr.) Bigeard & A. Jacq., Flore des Champignons Supérieurs du Département de Saône-et-Loire: 247 (1898) [MB653895] Krombholzia duriuscula (Schulzer ex Kalchbr.) E.-J. Gilbert, Les Bolets: 118 (1931) [MB630609] Boletus rufus subsp. duriusculus (Schulzer ex Kalchbr.) Maubl., Les Champignons Comestibles et Vénéneux. Ed. 2 2: 156 (1928) [MB846909] Boletus rufus var. duriusculus (Schulzer ex Kalchbr.) Bataille, Bulletin de la Société d Histoire Naturelle du Doubs 15: 32 (1908) [MB846937] Trachypus scaber var. duriusculus (Schulzer ex Kalchbr.) Vassilkov, Botanicheskie Materialy Otdela Sporovyh Rastenii Botanicheskogo Instituta Imeni V. L. Komarova Akademii Nauk SSSR 11: 138 (1956) [MB846938] Boletus scaber var. duriusculus (Schulzer ex Kalchbr.) Jacz., Opredielitel Gribov" Ed. 2. Tom" I. Sovershennye Griby: 593 (1913) [MB846939] Trachypus duriusculus (Schulzer ex Kalchbr.) Konrad & Maubl., Encyclopédie Mycologique 20: 117 (1952) [MB846940]