Abstract. Devillers, P. & Devillers-Terschuren, J.- Epipactis spiridonovii P. Devillers & J. Devillers-Terschuren and the group of Epipactis atrorubens [Natural. belges 80 (Orchid. 12) (1999): 286-291]. Epipactis spiridonovii was described in 1996 from the Pirin range in Bulgaria. Photographic documentation of the species is presented and its main differentiating characters within the group of Epipactis atrorubens are summarised. The flowers combine the small size characteristic of Epipactis parviflora and Epipactis subclausa (Epipactis thessala) with the extensive and heavy ornamentation of Epipactis atrorubens and Epipactis microphylla. They are unique in the prevalence of yellow pigments, particularly on the outer surface of the perianth. The leaves are flat, not keeled, green with no purple suffusion, relatively large, broad, and less crowded towards the foot of the stem than in most other forms of the group.

Key-Words: Orchidaceae, Epipactis atrorubens group, Epipactis spiridonovii, Bulgaria.