An integrative approach to delimiting species in a rare but widespread mycoheterotrophic orchid.

In the spirit of recent calls for species delimitation studies to become more pluralistic, incorporating multiple sources of evidence, we adopted an integrative, phylogeographic approach to delimiting species and evolutionarily significant units (ESU) in the Corallorhiza striata species complex. This rare, North American, mycoheterotrophic orchid has been a taxonomic challenge with regard to species boundaries, displaying complex patterns of variation and reduced vegetative morphology. We employed plastid DNA, nuclear DNA, and morphometrics, treating the C. striata complex as a case study for integrative species delimitation. We found evidence for differentiation of the endangered C. bentleyi (eastern USA) + C. striata var. involuta (Mexico) from the remaining C. striata (= C. striata s.s.; USA, Canada, Mexico). Corallorhiza striata involuta and C. bentleyi, disjunct by thousands of kilometers (Mexico-Appalachia), were genetically identical but morphologically distinct. In light of ...