The monophyly and rapid evolution of <i>Gentiana</i> sect. <i>Chondrophyllae</i> Bunge s.l. (Gentianaceae): evidence from the nucleotide sequences of the internal transcribed spacers of nuclear ribosomal DNA

The nucleotide sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA of 24 representative species of sect. <i>Chondrophyllae s.l. </i> have been determined and analysed phylogenetically, together with some species of other sections of the genus <i>Gentiana</i>. The ITS sequences strongly support the monophyly of the sect. <i>Chondrophyllae s.l. </i> as a whole complex including various different dysploid cytotypes. Species, such as <i>G. boryi</i> and <i>G. pyrenaica</i>, that had been split into distinct genera by some cytotaxonomists have been proven to be closely related. However, the ITS sequences do not provide sufficient information to make a robust estimation of the phylogenetic relationships among the closely related species and dysploid cytotypes of the complex, beyond recognizing their monophyly and rapid evolution.