Morphological differentiation among closely related species with disjunct distributions:: a case study of Mediterranean Cyclamen L. subgen. Psilanthum Schwarz (Primulaceae)

In Cyclamen subgenus Psilanthum, previous authors have recognized three species (C. repandum, C. balearicum and C. ereticum), with C. repandum subdivided into three subspecies (ssp. repandum, ssp. peloponnesiacum and ssp. rhodense), and two varieties (var. vividum and var. peloponnesiacum?) within C. repandum ssp. peloponnesiacum. To examine the validity of this classification and the degree of morphological differentiation among closely related endemic taxa with disjunct distributions, we undertook analyses of three quantitative and eight qualitative morphological traits of flowers and leaves, most of which have previously been used without statistical comparison in the classification of the different taxa. Cyclamen balearicum showed high levels of morphological differentiation from all other taxa in subgenus Psilanthum consistent with its specific status. In contrast, morphological differentiation between C. creticum and subspecies of C. repandum was similar to that among the three subspecies of C. repandum. When compared with a recent molecular phylogeny of this subgenus, our results suggest that C. creticum may best be described as a geographical subspecies of C. repandum. The two varieties of C. repandum ssp. peloponnesiacum showed few significant differences for individual traits and their overall morphology is very similar to each other. The morphology of plants at three sites on Corsica strongly suggest, consistent with molecular data, the occurrence of hybrid populations between C. balearicum (outside of its previously recognized distribution) and local C. repandum. (C) 2002 The Linnean Society of London.