Genetic relationships of Mimulus michiganensis comb. et stat. nov., formerly known as M. glabratus var. michiganensis, and two related species that have been implicated in its origin, M. glabratus var. jamesii and M. guttatus, were studied using random amplified polymorphic DNA (RAPD) markers. Genetic similarities were calculated based on the RAPD data using Jaccard's coefficient and used to construct a UPGMA phenogram. All individuals of M. michiganensis were highly similar to each other and formed a distinct cluster in the phenogram. This cluster was nested among the individuals of M. glabratus var. jamesii, and the resulting cluster was, in turn, nested within the individuals of M. guttatus. These findings, in agreement with earlier morphological and crossing studies, support the elevation of the taxon in rank from variety to species; accordingly, the new combination M. michiganensis was established. No evidence was found to support earlier hypotheses of a role of M. guttatus in the origin of M. michiganensis through hybridization with M. glabratus var. jamesii or through direct ancestry via an aneuploidy event. The results are consistent with a close relationship between M. michiganensis and M. glabratus var. jamesii.

Communicating Editor: Thomas G. Lammers