A cytological study on Ophrys (Orchidaceae) in Italy: New evidence and the importance of polyploidy

Abstract

This paper presents a cytological study of two recently described species of Ophrys from the Apulia region, which is one of the most important diversification centres of the genus. The basic chromosome number was x = 18 for the two species. Ophrys peucetiae Lozito, D'Emerico, Medagli & Turco has the karyotype 2n = 2x = 36: 24 m+12 sm, and O. pseudomelena Turco, Medagli & D'Emerico has 2n = 2x = 36: 30 m+6 sm. As observed in the O. fusca group, in O. pseudomelena, metacentric chromosomes predominate over submetacentric ones. In contrast, Ophrys peucetiae has a more evolved character, as seen in the standard karyotype of O. fuciflora s.l. On average, Ophrys peucetiae exhibited a more asymmetrical karyotype than O. pseudomelena. Variations in morphology and size in chromosome pair 1 were observed within both species. Studies on chromosome numbers in Ophrys taxa from Apulia and Sardinia revealed triploidy in Ophrys morisii (Martelli) Soò and tetraploidy in O. apulica (O. Danesch & E. Danesch) O. Danesch & E. Danesch and O. forestieri (Rchb. f.) Lojac. ( = O. lupercalis Devillers Tersch. & Devillers). The significance of the results is discussed in relation to previous information for this genus.

Keywords::

• Chromosomal indices
• karyomorphology
• Ophrys
• polyploidy
• speciation

Acknowledgement

The authors would like to thank Prof. Antonio Scrugli for providing the samples of O. morisii from St. Castiadas-Solanas (Cagliari).