Abstract. Delforge, P. - The robust Vanilla Orchid of the Mount Cenis (Savoy, France) [Natural. belges 84 (Orchid. 16) (2003): 117-132]. New genetic data and personnal field research have led to reconsider the taxonomic status of Gymnadenia (Nigritella) cenisia, a robust diploid Vanilla Orchid described from Mt. Cenis in 1998. The distinction of G. cenisia from G. rhellicani (= Nigritella nigra s.l. auct. pl.) is difficult. The two taxa are syntopic, their flowering times overlap widely as well as all the characters considered as diagnostic by authorsÕ description, i.e. flowers colour, lip opening, plant height, leaves number, and flowers number. Consequently, the two published keys integrating G. cenisia do not work on the field and numerous individuals are not attributable to one or to the other taxon. Observations of intrapopulational variation in 1999 and 2002, comparison of populations from Mt. Cenis (France) with one G. rhellicani population from Mt. Falakron (Northern Greece), and recent publishing of allozyme data used to estimate levels of variation inside the Vanilla Orchids have shown that G. cenisia is very probably a part of the continuous variation of G. rhellicani. To take into account the unusualy large inflorescence and the general robustness of some G. rhellicani around the Mt. Cenis, G. rhellicani var. robusta (var. nova) is described here. A list of 14 localities of G. rhellicani var. robusta, prospected in July 1999 and 2002, is provided.

Key-Words. Orchidaceae, genus Gymnadenia; Nigritella nigra s.l. auct. pl., Gymnadenia cenisia, G. rhellicani, G. rhellicani var. robusta var. nova; flora of France, Alps, Savoy, Greece.