Abstract. BAETEN, F., DIERCKX, J. & DELFORGE, P.- Presence in Belgium of a ×Dactylodenia, intergeneric natural hybrid between Dactylorhiza and Gymnadenia  [Natural. belges 92 (Orchid. 24): 45-70].
The first certain finding in Belgium of a natural intergeneric hybrid between Dactylorhiza and Gymnadenia is reported. Particularities and history of the site are evoked. It is the “Thier ą la Tombe”, a well-known nature reserve located at “Montagne Saint-Pierre” (Province of LiŹge, Wallonia). The hybrid is described in detail. Its parents are Gymnadenia conopsea var. conopsea and a member of the Dactylorhiza maculata species group difficult to identify. The difficulties to distinguish D. fuchsii from D. maculata in continental Europe are evoked. After a careful examination of the few individuals present on the site, a chalk grassland, it is concluded that they represent in all likelihood D. fuchsii with a more or less ‘maculata-like’ labellum. The nomenclatural difficulties of naming the hybrid Dactylorhiza fuchsii × Gymnadenia conopsea are mentioned. It appears that its correct name is ×Dactylodenia sancti-quintinii (GODFERY) J. DUVIGNEAUD. The European distribution and the iconography of ×Dactylodenia sancti-quintinii are evoked. Two previous mentions of the presence of ×Dactylodenia sancti-quintinii in Belgium are examinated; the oldest one is doubtful, the other erroneous.

Key-Words: Orchidaceae, Dactylorhiza maculata species group, Dactylorhiza fuchsii, Dactylorhiza maculata, Gymnadenia conopsea, ×Dactylodenia, ×Dactylodenia sancti-quintinii. Flora of Belgium, Wallonia, province of LiŹge, Montagne Saint-Pierre.