SYSTEMATIC, BIOGEOGRAPHIC AND TAXONOMIC STUDIES ON TRICHANTHECIUM MORRONE & ZULOAGA (POACEAE, PANICOIDEAE, PANICEAE) AND ALLIED TAXA

Phylogenomics. Gramineae. Panicum. Savannas.

Trichanthecium Zuloaga & Morrone (Poaceae, Panicoideae, Paniceae) was described based on morphological, anatomical and molecular data which supported the segregation of 38 species previously included in Panicum sect. Parvifolia and Panicum sect. Verruculosa. They are annual or perennial herbs, with synflorescences in panicles, bearing solitary spikelets and upper anthecium with bicellular microtrichomes, hence the name of the genus. Currently the genus is composed of 39 species distributed in tropical and subtropical areas of Africa and America, especially in savannas with sandy and rocky soils, where they exhibit a high level of endemism in the regions of the Guiana Shield and eastern Brazil (Espinhaço range). The last phylogenies focusing on the tribe Paniceae presented the genus with low resolutions, and important taxa could not be sampled. In addition, a group of eight African species of Panicum s.l. was recovered in an uncertain position in Trichanthecium, suggesting that the group is paraphyletic. We hope that a larger taxa sampling and the use of other methodologies for phylogenetic analysis (next-generation sequencing) and an in-depth biogeographic study can elucidate the gaps in the knowledge of the genus, and provide subsidies for conservation policies. In this context, the aim of the project is to conduct a phylogenomic, biogeographic and taxonomic study of Trichanthecium and allied taxa. The thesis will be organized into three chapters, in the form of scientific papers: 1) Phylogenetic relationships of the genus Trichanthecium and allied taxa; 2) Biogeography and evolution of the genus Trichanthecium; 3) Taxonomic synopsis of the American species of Trichanthecium. Collection expeditions were carried out in the states of Pará (Marajó Island and Maicuru Biological Reserve), Goiás (Chapada dos Veadeiros) and Minas Gerais (Espinhaço range). In addition to the material collected, 3,555 exsiccates deposited in national and international herbaria will be analyzed; 1,600 samples have already been examined. Fifteen of the 40 terminals proposed for sequencing the plastome are currently being processed. Biogeographical analysis will be carried out on the basis of the phylogenetic trees and the dataset of geographical distribution of the species. The taxonomic treatment of the American species of Trichanthecium possess, a priori, 38 taxa and will include nomenclatural headings, morphological descriptions, geographic distribution and habitat data, conservation status and micromorphological analysis of the upper anthecium, to verify the ornamentation of the microtrichomes.