Macleania and Psammisia are two genera of blueberries found primarily at higher elevations throughout the Neotropical cordillera. These genera have been considered closely related to each other and distinct from other tropical Vaccinieae based on features of the androecium. As part of a revision of these taxa, a molecular systematic study was performed using nuclear ribosomal internal transcribed spacer (nrITS) and the chloroplast gene matK for 29 species of Macleania and Psammisia (i.e., about 30% of the taxa currently recognized within the genera) and selected Vaccinieae. Analyses of the combined data indicate that most of the taxa currently within Macleania and Psammisa form a clade. (Exceptions to this are Macleania megabracteata and Psammisia urichiana which consistently fall outside the group.) However, branch lengths are very short at the base of this clade and therefore bootstrap support for the group is below 50%. Macleania and Psammisia are both paraphyletic in this study. The results indicate that Macleania is, for the most part, derived from within Psammisia. Psammisia dolichipoda and Ps. sodiroi are indicated as sister and this relationship has strong bootstrap support. These two species represent the "globosa" subgroup within Psammisia. However, the results of this study do not support any of the other species groups suggested in previous studies for either Macleania or Psammisia. This study suggests that Macleania and Psammisia are closely related but that neither is monophyletic as currently recognized. Further resolution of species relationships is likely to require a more variable data source. Larger scale analyses based on combined analysis of matK, ITS and the chloroplast trnT-L spacer indicate that Macleania and Psammisia fall within a large clade that includes other Neotropical genera such as Satyria and Sphyrospermum.

Key words: blueberries, Macleania, molecular systematics, Neotropical, Psammisia, Vaccinieae