Filogenia, taxonomia e distribuição geográfica de Terminalia L. (Combretaceae) na região neotropical com ênfase nas espécies ocorrentes no Brasil

Abstract

Terminalia L., a pantropical genus of Combretaceae, comprehends trees, rare shrubs, with variable morphological characters, mainly the leaves and flowers arrangement in the inflorescences. The genus has been the subject of recent molecular phylogenetic studies that allowed the expansion of its concept. Despite this, the infrageneric circumscription of Terminalia s.l. remains incomplete, mostly for the clade that includes the Neotropical species. The aims of this study were to propose a molecular phylogenetic hypothesis for Terminalia s.l., mainly, discussing the relationships among Neotropical taxa and the concept of the current sections of the genus; in addition, a floristic-taxonomic treatment for the Brazilian species of Terminalia s.s., including aspects about conservation and distribution patterns. Therefore, the phylogenetic relationships were reconstructed by Bayesian Inference, using nuclear genomic (ITS) and plastid markers (matK and trnH-psbA), and included 105 samples from 77 representatives of the genus (27% of the total spp.). For taxonomic studies, field trips were carried out to collect botanical material and observe plants in their habitat. In addition, about 5000 specimens deposited in 90 Brazilian and foreign herbariums, including typecollections, were analyzed. As results obtained, it was defined that Terminalia s.s., in Brazil, comprises 22 species, six of which are endemic, characterized by the presence of alternate leaves arranged at the apex of the branches, usually, with domatia and petiolar glands, flowers in panicles of spikes or spikes and betulid fruits, rare drupe, 2−5(−6)-winged. The largest number of species of the genus in the Neotropical region was registered in Brazil (22 spp.), which, therefore, represents the center of diversity and richness in the region. In Brazil, the species are concentrated in the eastern portion of the country, specifically in the south of the Northeast (Bahia) and Southeast in the Atlantic Rainforest domain. A new species of Terminalia s.s. for science was described in that study, T. nildae R.T.M. Ribeiro, Loiola & M.F.Sales. In addition, four new synonyms were proposed, two sections were recircumscribed, two taxa reestablished and new occurrences (12) for the Brazilian territory were reported. Phylogenetic studies have shown that the genus is monophyletic under the current delimitation, presenting in its topology two strongly supported clades. These two larger clades possibly reflect two lineages influenced by the patterns of geographic distribution of their taxa. Interspecific relationships proved to be strongly, moderately to weakly supported; in addition, there were fragility in the currently accepted sectional classification, in particular, in relation to sections that include neotropical taxa.