To clarify relationships within the predominantly Neotropical and exclusively fleshy‐fruited Myrteae (49 genera and c. 2,500 species), we provide a phylogenetic hypothesis for evolutionary relationships between 31 of these genera by analyzing nuclear ITS and ETS ribosomal DNA, and plastid psbA‐trnH and matK DNA sequences from 75 Myrteae species and 13 outgroup taxa using parsimony and Bayesian inference. Four morphological characters are epitomized on the resulting trees, and biogeographical analyses are also performed. Myrteae are monophyletic, comprising seven clades plus two isolated taxa of unclear relationships. Morphological characters exhibit homoplasy, although in combination are useful for clade diagnosis. Biogeographical analyses are inconclusive regarding the ancestral area of the tribe, but South American colonization before northern radiation via the Andes appears likely. The largest genera, Eugenia and Myrcia s.l., have western and southeastern South American origins, respectively.

Myrteae (c. 2500 species; 51 genera) is the largest tribe of Myrtaceae and an ecologically important groups of angiosperms in the Neotropics. Systematic relationships in Myrteae are complex, hindering conservation initiatives and jeopardizing evolutionary modelling. A well-supported and robust phylogenetic hypothesis was here targeted towards a comprehensive understanding of the relationships within the tribe. The resultant topology was used as a base for key evolutionary analyses such as age estimation, historical biogeography and diversification rate patterns. One nuclear (ITS) and seven chloroplast (psbA-trnH, matK, ndhF, trnl-trnF, trnQ-rps16, rpl16 and rpl32-trnL) DNA regions for 115 taxa representing 46 out of the 51 genera in the tribe were accessed and analysed using maximum likelihood and Bayesian inference tools for phylogenetic reconstruction. Dates of diversification events were estimated and contrasted using two distinct fossil sets (macro and pollen) in BEAST. The subsequent dated phylogenies were compared and analysed for biogeographical patterns using BioGeoBEARS and diversification rates using BAMM. Myrteae phylogeny presents strong statistical support for three major clades within the tribe: Australasian group, Myrtus group and Main Neotropical Lineage. Dating results from calibration using macrofossil are an average of 20 million years older and show an early Paleocene origin of Myrteae, against a mid-Eocene one from the pollen fossil calibration. Biogeographic analysis shows the origin of Myrteae in Zealandia in both calibration approaches, followed by a widespread distribution throughout the still-linked Gondwana continents and diversification of Neotropical endemic lineages by later vicariance. Best configuration shift indicates three points of acceleration in diversification rates, all of them occurring in the Main Neotropical Lineage. Based on the reconstructed topology, several new taxonomic placements were recovered, including: the relative position of Myrtus communis, the placement of the Blepharocalyx group, the absence of generic endemism in the Caribbean, and the paraphyletism of the former Pimenta group. Distinct calibration approaches affect biogeography interpretation, increasing the number of necessary long distance dispersal events in the topology with older nodes. It is hypothesised that biological intrinsic factors such as modifications of embryo type and polyploidy might have played a role in accelerating shifts of diversification rates in Neotropical lineages. Future perspectives include formal subtribal classification, standardization of fossil calibration approaches and better links between diversification shifts and trait evolution.

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Eugenia, comprising ca. 1100 species, is the largest genus of Neotropical Myrtaceae. Eugenia sect. Umbellatae (formerly referred to as “clade 9”) is the most speciose lineage of Eugenia. This study aims to better delimit E. sect. Umbellatae, to identify and understand relationships between manageable subgroups of this large clade for future discrete systematic studies and to explain biogeographical patterns in the genus. In total, 103 samples were used in this study. These include representatives of the nine clades of the “Eugenia group” with a particular focus on Eugenia clade 9, representing the morphological and geographical diversity found in the genus. Phylogenetic reconstructions were performed using maximum likelihood (ML) and Bayesian inference (BI) for the combined dataset, using the markers ITS, rpl16, psbA–trnH, rpl32–trnL, trnQ–rps16. The resultant tree was fossil calibrated and used for historical biogeographical analysis using DEC implemented in RASP. The mid Oligocene is the most likely period in which the crown node of Eugenia s.l. diversified. The earliest Eugenia appear to be associated with dry biomes and to have arisen from non–tropical southern South America, as did ancestors of the earliest American Myrteae. Eugenia subg. Pseudeugenia also most likely diversified in dry biomes, while E. subg. Hexachlamys and E. subg. Eugenia are likely to have diverged in the Atlantic Forests biome. Eugenia sect. Umbellatae is morphologically very variable; some clades can be circumscribed based on morphology while some remain morphologically undiagnosable. The study presented here provides discussion of the earliest origins of Eugenia and its response to climate–driven changes in the Neotropics as humid, forest biomes became more widespread in the Miocene. In addition, important practical conclusions are drawn regarding relationships within Eugenia. Three clades are newly classified as subgenera: E. subg. Pseudeugenia (including species of E. sect. Pseudeugenia); E. subg. Hexachlamys (including E. sect. Hexachlamys) and E. subg. Eugenia (including E. sect. Umbellatae,E. sect. Jossinia,E. sect. Phyllocalyx,E. sect. Pilothecium,E. sect. Racemosae,E. sect. Schizocalomyrtus, E. sect. Speciosae and Eugenia sect. Excelsae). Two previously unidentified clades are published as E. sect. Excelsae and recognized as E. sect. Jossinia, the latter consisting entirely of Old World species.