Phylogenetic relationships of Mediterranean Neottieae and Orchideae (Orchidaceae) inferred from nuclear ribosomal ITS sequences

Abstract

Sequence data for the internal transcribed spacer (ITS) region of nuclear ribosomal DNA were collected from 27 terrestrial Mediterranean orchid species. These data were included in parsimony (MP) and maximum likelihood (ML) analyses. Tree topologies from the parsimony and maximum likelihood analyses were largely congruent. Both topologies shows that Neottieae are strongly supported as monophyletic (MP = 100% and ML = 86%). Within Orchideae, Dactylorhiza + Orchis + Neotinea are sister groups; the Himantoglossum + Anacamptis clase is well delimited by the cytological synapomorphy of n = 18, in both parsimony and maximum likelihood analysis; Serapias is monophyletic according to molecular evidence, though it does not exist unequivocal distinction between the tetraploid S. lingua and the remaining diploid species; section Pseudophrys of genus Ophrys is isolated, showing unequivocal morphological (type of labellum and pollination) and karyological (tetraploid species with 2n = 72) cohesion.