Phylogeny and biogeography of the hyper–diverse genus Eugenia (Myrtaceae: Myrteae), with emphasis on E. sect. Umbellatae, the most unmanageable clade

Abstract

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.

Biogeography of Stigmaphyllon (Malpighiaceae) and a Meta-Analysis of Vascular Plant Lineages Diversified in the Brazilian Atlantic Rainforests Point to the Late Eocene Origins of This Megadiverse Biome

“…12.0 Mya in the MRCA of S. sinuatum group, from the BAFs to the Amazon rainforest. The same pattern of diversification was recorded in other plant lineages, with Atlantic rainforest MRCAs colonizing the Amazon rainforest at this time, such as Eugenia L. clade G [ 55 ]. At least 50 dispersal events occurred between the Atlantic and Amazon rainforests [ 16 ].…”

Diversification of New World Cleomaceae with emphasis on Tarenaya and the description of Iltisiella, a new genus

“…These environmental factors seem to be relevant to diversification of many groups in these areas, as experienced for Dolichandra (Bignoniaceae; Fonseca & Lohmann, ); Gesneriaceae lineages (Roalson & Roberts, ); Campylocentrum Benth. (Orchidaceae; Pessoa & al., ); Eugenia L. (Myrtaceae; Mazine & al., ) and Amorimia W.R.Anderson (Malpighiaceae; Almeida & al., ).…”

As sementes de Eugenia spp. (Myrtaceae) e seus novos conceitos sobre propagação

“…A subtribo Eugeniinae, que compreende o gênero Eugenia, é caracterizada por seus embriões eugenioides, constituídos por duas formas básicas: (1) cotilédones grossos, separados, plano-convexos e hipocótilo em uma pequena protrusão; e (2) cotilédones fundidos parcial ou completamente em uma única massa e hipocótilo nãodistinguível (Landrum & Kawasaki 1997). E Eugenia, ainda hoje, é considerado o maior gênero de Myrtaceae neotropical (Mazine et al 2018), sendo o gênero de angiospermas com maior número de espécies no Brasil (BFG 2015) e o segundo gênero de árvores mais diverso em espécies do mundo (Beech et al 2017), compreendendo atualmente cerca de 1.100 espécies (WCSP 2017).…”