Beschreibung:
<jats:title>Abstract</jats:title><jats:p>In an effort to clarify the patterns of chromosome evolution in <jats:italic>Ophrys</jats:italic> sect. <jats:italic>Pseudophrys</jats:italic> (Orchidaceae), chromosome counts were made of 18 O. sect. <jats:italic>Pseudophrys</jats:italic> taxa from the central–western Mediterranean Basin (Iberian Peninsula and North Africa). The present results provide, for the first time, the chromosome numbers of O. <jats:italic>algarvensis, O. arnoldii, O. bilunulata</jats:italic> and <jats:italic>O. dianica</jats:italic>; four other taxa (<jats:italic>O. atlantica, O. lupercalis, O. fusca, O. sicula</jats:italic>) yielded chromosome numbers not previously reported for the Iberian Peninsula. The results support the idea that the basic plesiomorphic number of <jats:italic>Ophrys</jats:italic> is <jats:italic>x</jats:italic> = 18, with 2n = 36 in most species. About 40% of the specimens were polyploids. Karyomorphological data do not support classification of the investigated species into groups. However, the data reveal some geographical differentiation and suggest a possible direction of chromosomal evolution in <jats:italic>Ophrys</jats:italic> sect. <jats:italic>Pseudophrys</jats:italic>.</jats:p>