And the twain shall meet at the end: a phylogeny of Myrcianthes (Myrtaceae, Myrteae) with phytogeographic and morphological insights

Background and aims – Myrcianthes is a New World genus of Myrtaceae with 36 species, diverse in the Andes, and often dominant in montane forests. It is found from the Pacific to the Atlantic, from sea level to 3729 m, and its total latitudinal range is almost 62°. Its old age, combined with a wide ecological and geographic range, and the many narrow-endemic species, make it of phytogeographic and evolutionary interest. Material and methods – Altitudinal, geographic, and wood anatomy data of the genus were compiled from literature and online herbaria and curated to eliminate errors and produce a reliable dataset. ML and Bayesian phylogenetic trees based on ITS, ETS, mat K, and psb A- trn H of 11 Myrcianthes species, in a matrix of 123 species, were constructed. The Bayesian tree was calibrated with three macrofossils and three secondary calibration points and used to infer biogeographic history and to estimate ancestral ranges using BioGeoBEARS. Key results – Myrcianthes has the widest combined altitudinal/latitudinal range in Myrtaceae. Narrow-endemic species are concentrated either in the high-latitude lowlands or the low-latitude highlands. Myrcianthes diverged from Eugenia in the early Oligocene but did not diversify before the mid-Miocene (later than Eugenia ). Myrcianthes diversified from the south into South America, Central America, and the Caribbean. Its ancestral range emerged as the Chacoan/Paraná dominions, consistent with the extinct temperate/subtropical austral forest. After splitting from M. coquimbensis , endemic to Chile, the main clade divided into a lowland clade (most diverse in eastern South America) and a highland clade (most diverse in the Andes). The clades are sympatric near the inferred root of the tree and probably meet again in Colombia and Venezuela. Myrcianthes wood anatomy appears to differ from that of Eugenia by the occurrence of helical thickenings in the vessels and absence of prismatic crystals in the axial parenchyma, but sampling is still incomplete.