Conservation genetics and taxonomic status of the rare Kentucky lady's slipper: Cypripedium kentuckiense (Orchidaceae)

Cypripedium kentuckiense is a recently described rare orchid found in Arkan sas (predominantly) and in eight other states. Much debate has focused on w hether this taxon should be recognized as a distinct species or considered to be an extreme manifestation of the variability present in the widespread taxon Cypripedium parviflorum var, pubescens. In this study, 12 isozyme lo ci were analyzed for 14 populations of C. parviflorum var. pubescens and ei ght populations of C. kentuckiense. These data were used to examine the gen etic similarity of these taxa, assess whether isozyme data support the cont inued recognition of C. kentuckiense as a distinct species, and assess whet her a newly discovered disjunct Virginia population of C, kentuckiense is g enetically isolated from other C. kentuckiense populations. The isozyme dat a revealed that the two taxa are very closely related with a high interspec ific genetic identity. However, C. kentuckiense populations contain a subse t of the variation present in C. parviflorum var, pubescens, and they have expected levels of heterozygosity that are one-quarter that of C. parviflor um var. pubescens populations. Cypripedium kentuckiense also possesses one widespread unique allele and a unique multilocus genotype. These data sugge st that C. kentuckiense should be recognized as a distinct species, possibl y of recent origin from C. parviflorum. Lastly, the isozyme data support th e hypothesis that gene flow between the Virginia population and other popul ations of C. kentuckiense has been restricted.