Notulae ad Floram agaricinam neerlandicam — XIV. A noemnclatural note on Rhodocybe truncata

Agaricus truncatus Schaeff. (Fungi Bavariae, pl. 251. 1763) is variously interpreted as a species of Hebeloma and Rhodocybe. Although the type-plate is not so easy to interpret, the adnate, sinuate lamellae, sordid spore print, and red-brown, truncate pileus give way to the idea that Fries (1838) was right in placing Agaricus truncatus in tribus Hebeloma. This opinion was followed by e.g. J. Lange (1938) and Moser (1978, 1984). Quélet (1880) had another opinion on Agaricus truncatus and placed it in the genus Tricholoma. This concept is known by modern mycologists as Rhodocybe truncata (Schaeff.) Singer. Still Tricholoma truncatum (Schaeff.) Quél., Rhodopaxillus truncatus (Schaeff.) Maire, and Rhodocybe truncata (Schaeff.) Singer all have the same type, viz. Schaeffer’s plate, and must be considered as synonyms of Hebeloma truncatus (Schaeff.) Kumm. It is clear that the binomial Rhodocybe truncata cannot be used for Quélet’s fungus. Therefore Bon (1985) was wrong in creating the so-called new combination Rhodocybe truncata (Quél.) Bon. The epithet truncata cannot be ascribed to Quélet, as is pointed out above. Even if Bon had been right, the name Rhodocybe truncata (Quél.) Bon would have been a heterotypical homonym of Rhodocybe truncata (Schaeff.) Singer and could not have been used for that reason.