Revisiting of the type material of Fagus haidingeri Kováts

Fagus haidingeri Kováts is a characteristic Miocene–Pliocene fossil-taxon widely recorded across Europe and western Asia. Because its type material was believed to be lost no direct verification of its diagnostic features has been attempted. The type material described by Kováts (1856) from the Serravallian (regional stratigraphy: Sarmatian) deposits of Erdőbénye–Barnamáj were considered missing for a longed period, leaving the species concept dependent largely on historical illustrations. Here we report the presence of both original specimens in the Hungarian Natural History Museum, including the one corresponding to the lectotype designated by Denk (2004). The investigation of the type material enables the first direct assessment of its foliar morphology. The leaves display consistently craspedodromous secondary venation together with a characteristic suite of traits, including convex intersecondary margin regions, a narrow ovate to elliptic to elongate lamina, and small, blunt marginal teeth with concave distal and straight to slightly convex proximal flanks. This combination of characters agrees with the broad species concept formulated by Knobloch (1969) and synthesised by Denk (2004) and provides clear criteria for distinguishing Fagus haidingeri from the closely related Neogene taxa Fagus gussonii A.Massal. and Fagus castaneifolia Unger. By re-evaluating the type specimens, this study restores a secure nomenclatural and morphological foundation for Fagus haidingeri and provides a sound basis for future taxonomic, stratigraphic and evolutionary research on Neogene members of the beech lineage. • Original type material of Fagus haidingeri revisited. • Lectotype of Fagus haidingeri confirmed from Kováts' original material. • Craspedodromous venation and subsidiary teeth documented directly from type material. • Emended diagnosis of Fagus haidingeri based on type material. • Taxonomic framework for Neogene Eurasian beeches supplemented.