BIOSYSTEMATIC INVESTIGATION OF ASPLENIUM-LEPIDUM COMPLEX

Twenty-nine populations of 3 closely related taxa, A. lepidum, A. haussknechtii and A. samarkandense, were raised together in cultivation. There is considerable inter-population variation, and the ranges of variation of the 3 spp. overlap. Cytogenetic investigation of artificial hybrids has shown that the 3 taxa are all allotetraploid and that they share the same diploid parents, A. aegaeum and A. ruta-muraria ssp. dolomiticum. Analysis of F1 and F2 hybrids between different populations indicates high inter-fertility. The aggregate is re-defined as a single polymorphic species (A. lepidum) consisting of 2 sspp. (ssp. lepidum and ssp. haussknechtii ) Brownsey comb. nov. (A. haussknecktii) distinguished primarily by gland and sporangial characters. A. samarkandense is reduced to a variety of ssp. haussknechtii. A. lepidum ssp. haussknechtii var. samarkandense comb. nov. It is suggested that the 2 ssp. have had separate geographical origins from different morphological variants of the same diploid parents, but the polymorphic nature of the aggregate is principally due to divergent evolution in small populations isolated on limestone mountains in southern Europe and western Asia.