Phylogenetic relationships among Vaccinium sections Macropelma, Myrtillus and Hemimyrtillus have been the subject of much debate but hypotheses about evolutionary relationships among these taxa have not been tested using a cladistic framework. These taxa have been proposed as close relatives and they share, along with sect. Oxycoccoides, the character of buds covered by two partially fused prophylls. However, the monophyly of these sections has not been assessed and there has been disagreement as to their species content. Vaccinium sect. Macropelma as currently recognized includes four species: Vaccinium dentatum, V. calycinum, and V. reticulatum from the Hawaiian Archipelago and V. cereum from southern Polynesia. While most investigators agree that the Hawaiian taxa represent a natural group, the phylogenetic position of V. cereum has been the subject of much discussion. Some authors place V. cereum in sect. Macropelma, while others feel that it is closer to other Pacific sections of Vaccinium (i.e., sect. Bracteata). The goals of this study were to use molecular data in a phylogenetic analysis to assess the monophyly of sections Macropelma, Myrtillus and Hemimyrtillus and to determine their phylogenetic position in tribe Vaccinieae. Molecular data from the chloroplast genes matK and ndhF and nrITS for approximately 50 species of Vaccinieae and three outgroups from "Andromedeae" were analyzed, individually and in combination, using parsimony. Results show that both sect. Myrtillus and sect. Hemimyrtillus are paraphyletic. Hawaiian representatives from sect. Macropelma form a well-supported clade derived from within sect. Myrtillus. However, the Polynesian V. cereum may be of hybrid origin. The Macropelma + Myrtillus clade is sister to a clade which contains V. erythrocarpon (sect. Oxycoccoides) sister to the two Asian representatives from sect. Hemimyrtillus, V. hirtum and V. smallii. The three Mediterranean taxa from sect. Hemimyrtillus form a clade weakly supported as sister to the rest of tribe Vaccinieae.

Key words: Ericaceae, Hawaiian blueberries, Macropelma, Myrtillus, Vaccinieae, Vaccinium