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Myrtaceae are a large family of trees and shrubs, including ca. 2500 species within the predominantly Neotropical and taxonomically problematic tribe Myrteae. Nearly 500 species of Myrteae are endemic to the Caribbean Islands Biodiversity Hotspot, but few have been represented in phylogenetic systematic studies to date. The major goals of this survey are to identify the main lineages of Myrteae present in the Greater Antilles and potential clades for further investigation. Specific objectives are to evaluate the monophyly and placement of the following: (1) the three genera of Myrtaceae considered endemic to the Caribbean Islands (Calyptrogenia, Hottea, Mitranthes); (2) Calycolpus and Pseudanamomis sensu Bisse; and (3) Greater Antillean species of Plinia. To accomplish these aims, species of Myrtaceae representing all genera native to the Greater Antilles were sampled from across the region for placement within previously established phylogenetic frameworks for Myrteae and the large genus Eugenia. In total, 160 terminal taxa of Myrtaceae (89 Caribbean Islands endemics) were analyzed for this study. Phylogenetic inference was conducted by maximum parsimony and Bayesian methods on alignments of DNA sequence data from one nuclear (ITS) and three chloroplast (psbA‐trnH, ndhF‐rpl32, trnL‐trnF) regions. Results of both types of analysis were congruent with each other and with the major clades recovered in previous studies, but some conflict was observed between nuclear and chloroplast regions involving congeneric species. Calycorectes (= Hottea) ekmanii from eastern Cuba was found to be closely related to Calycolpus within subtribe Myrtinae. Subtribes Myrciinae, Pliniinae, Pimentinae (Pimenta and Psidium groups) and Eugeniinae contained other Greater Antillean species. Sampled species of Plinia from Cuba emerged within Myrciaria, and Mitranthes was found to be non‐monophyletic. All sampled species of Eugenia endemic to the Caribbean fell within E. sect. Excelsae (including Calycolpus sensu Bisse), E. sect. Racemosae and E. sect. Umbellatae except for E. cycloidea, which was associated with the Old World species of E. sect. Jossinia. Within Eugenia sect. Umbellatae, Caribbean species formed two major clades, designated C1 and C2, containing species of Calyptrogenia and Hottea from southern Hispaniola, a polyphyletic Pseudanamomis sensu Bisse and the Lathberry Clade, a novel group of Eugenia species centered in Puerto Rico and the Virgin Islands. Calyptrogenia and Hottea species from southern Hispaniola are transferred to Eugenia along with Pseudanamomis nipensis, while Mitranthes species are transferred to Myrcia. Two additional combinations are made within Eugenia and Pimenta in accordance with the results, and lectotypes are designated as appropriate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The eco-evolutionary history of insular Caribbean Sticta was explored. • Species assemblages date back to the early Miocene and show strong biogeographic links to South America. • Colonization of the islands did not increase diversification rates. • Environmental variation most strongly explains taxonomic and phylogenetic turnover between island-level communities. Phylogenetic approaches to macroevolution have provided unique insight into evolutionary relationships, ancestral ranges, and diversification patterns for many taxa. Similar frameworks have also been developed to assess how environmental and/or spatial variables shape species diversity and distribution patterns at different spatial/temporal scales, but studies implementing these are still scarce for many groups, including lichens. Here, we combine phylogeny-based ancestral range reconstruction and diversification analysis with community phylogenetics to reconstruct evolutionary origins and assess patterns of taxonomic and phylogenetic relatedness between island communities of the lichenized fungal genus Sticta in the Caribbean. Sampling was carried out in the Greater Antilles (Cuba, Jamaica, Dominican Republic, and Puerto Rico) and Lesser Antilles (Dominica, Guadeloupe, and Martinique). Data for six molecular loci were obtained for 64 candidate Caribbean species and used to perform both macroevolutionary phylogenetics, which also included worldwide taxa, and phylobetadiversity analyses, which emphasized island-level communities. Our work uncovered high levels of island endemism (∼59%) in Caribbean Sticta. We estimate initial colonization of the region occurred about 19 Mya from a South American ancestor. Reverse migration events by Caribbean lineages to South America were also inferred. We found no evidence for increased diversification rates associated with range expansion into the Caribbean. Taxonomic and phylogenetic turnover between island-level communities was most strongly correlated with environmental variation rather than with geographic distance. We observed less dissimilarity among communities from the Dominican Republic and Jamaica than between these islands and the Lesser Antilles/Puerto Rico. High levels of hidden diversity and endemism in Caribbean Sticta reaffirm that islands are crucial for the maintenance of global biodiversity of lichenized fungi. Altogether, our findings suggest that strong evolutionary links exist between Caribbean and South American biotas but at regional scales, species assemblages exhibit complex taxonomic and phylogenetic relationships that are determined by local environments and shared evolutionary histories. [ABSTRACT FROM AUTHOR]