New cytological data in Ophrys sect. Pseudophrys Godfery and comparative karyomorphological studies in Ophrys L. (Orchidaceae)

Abstract

Eight species of Ophrys sect. Pseudophrys (Orchidaceae) were cytogenetically studied. The analysed species possess the most symmetrical karyotypes of the genus (M_CA ranged from 10.21 to 15.87 and CV_CL from 19.61 to 23.93) with 2n = 2x = 36, being composed of mainly metacentric chromosomes. The karyotype formulae were: 36m for Ophrys archimedea, 32m + 4sm for O. flammeola, 32m + 4sm for O. funerea, 36m for O. laurensis, 36m for O. lojaconoi, 34m + 2sm for O. lucifera, 34m + 2sm for O. obaesa and 36m for O. pallida. Karyotype morphometric characters were evaluated by calculating M_CA and CV_CL for the assessment of karyotype asymmetry, and CV_CI for the evaluation of heterogeneity in the position of the centromeres. The relationships between species were thus finally elucidated. The species characterised by wide distribution show greater karyomorphological distance than those with restricted distribution. The possible evolutionary role of chromosomal rearrangements as well as gene mutations in the speciation of Ophrys is discussed.

Keywords:

• Ophrys
• Pseudophrys
• chromosomal rearrangement
• karyotype evolution

Acknowledgements

The authors would like to thank Prof.ssa Giuseppina Bartolo for her helping during the samplings.