Abstract. Delforge, P. - Orchis and monophyly [Natural. belges 90 (Orchid. 22) (2009): 15-35. Even after the creation, around 1950, of the distinct genus Dactylorhiza gathering the ŌOrchisÕ with palmated root tubers, the rest of the genus Orchis remained species rich, comprising 7 species groups and seeming still heterogeneous. As a result, Vermeulenia was created in 1972 for the species of the Orchis papilionacea group, Anteriorchis in 1989 for the species of the Orchis coriophora group. More recently, genetic research has confirmed that Orchis is polyphyletic and an extensive taxonomic revision was published. Four monophyletic groups, based on O. palustris, O. papilionacea, O. coriophora, and O. morio respectively were placed in an expanded Anacamptis, whilst the Orchis tridentata group was placed in an expanded Neotinea. Consequently, Orchis s. str. comprises the O. mascula and the O. militaris species groups, with Aceras anthropophorum. This arrangement has not received an uninamous approval notably because of the conflicting results obtained by other approaches, mainly genetic, karyological and morphological, to the phylogenetics of Orchidinae, particularly for Anacamptis pyramidalis. The splitting of Orchis s.l. remains justified, but other fusions, incorporations, and separations were advocated.

In 2008, a formal proposition for another classification was made. Anacamptis and Neotinea remain monospecific, whilst Orchis s.l. is divided into 4 genera: (i) Orchis sensu strictissimo consisting of the O. militaris group and Aceras anthropophorum, (ii) Androrchis gen. nov. consisting of the O. mascula group, (iii) Odontorchis gen. nov. consisting of the O. tridentata group, and (iiii) Herorchis gen. nov. gathering the species of the Orchis palustris - papilionacea - coriophora - morio complex. This new classification was rapidly criticized mainly because (i) the splitting of Orchis s. str., which seems monophyletic, create a taxon apparently polyphyletic: Androrchis, (ii) Herorchis seems paraphyletic, and, furthermore, (iii) the name Vermeulenia (1972) has priority over Herorchis (2008) if Orchis papilionacea (= Vermeulenia papilionacea) is inserted into Herorchis.

Nevertheless, another classification is possible, which respects the geneticistsÕ requirement of monophyly, shows a strong correlation with the morphological and karyological evidences, and does not need numerous new names. (i) Neotinea expanded and Orchis s. str. comprising the O. mascula and the O. militaris species groups, with Aceras anthropophorum, are accepted, (ii) Anacamptis remains monospecific, (iii) the Orchis palustris - papilionacea - coriophora - morio complex is divided into Anteriorchis (monophyletic, 3 species, the former Orchis coriophora group), Herorchis (monophyletic, restricted to the 7 species of the former Orchis morio group), Paludorchis gen. nov. (monophyletic, comprising the 5 species of the former Orchis palustris group), and Vermeulenia (monophyly uncertain, comprising 3 species: the former Orchis papilionacea, O. collina, and O. cyrenaica). The nomenclatural changes necessited by this classification are formally made. A list of nothogenus and nothospecies subsequent to this changes is provided.

Key-Words: Orchidaceae, Systematics, Phylogenetics, Orchis s.l., Anacamptis, Anteriorchis, Herorchis, Paludorchis gen. novum, Vermeulenia.