Catasetum Rich. ex Kunth (Orchidaceae) : filogenia e monografia do gênero para a flora de Mato Grosso, Brasil

Abstract

The subtribe Catasetinae is the most prominent group in the Orchidaceae family and is divided into six genera: Catasetum Rich. ex Kunth, Clowesia Lindley, Cycnoches Lindley, Dressleria Dodson, Galeandra Lindley and Mormodes Lindley and is made up of more than 200 species, all restricted to Central and South America. The Catasetum genus is made up of 165 valid species and 16 natural hybrids, and is divided into subgenera, sections and subsections, based mainly on antenna morphology. The studies were carried out by consulting the collections of the main national herbariums and those from the state of Mato Grosso, in collections in the various vegetation types of Mato Grosso. All sequences from the total DNA collection obtained in this project were submitted to Genbank. So as to evaluate if the samples of different individuals form a specific monophyletic grouping and the relation between the species of the genus, standard phylogenetic approaches using Maximum Likelihood and Bayesian Analysis were used. Hence, this work proposes a phylogenetic hypothesis for the genus Catasetum, and its infrageneric classification, from the sequencing of nuclear and plastid DNA regions and morpho-anatomical data of 52 species which are representative of the genus considered for the subtribe Catasetinae: Catasetum, Clowesia, Cyanaeorchis, Cycnoches, Cyrtopodium, Dressleria, Galeandra, Grobya and Mormodes. We used ITS and ETS in this study. These markers show greater ability in delimiting species, showing better performance in inter-specific distance, differences between intra and inter-specific distribution distance, species recovery and coalescence analysis. This work generated relevant results as to the knowledge of the native flora of Mato Grosso, including the description of new species discovered during its development and sampling activities. Thereby new records were added to the list of native species and the distribution of several species of Catasetum was expanded, covering areas which are still little known. With all the additions obtained, the list of native Catasetum species of Mato Grosso reached the amount of 47 taxa. The subtribe Catasetinae was recovered as monophyletic, with high support, dated in approximately 22 Ma. The topology of the phylogenies obtained by the Bayesian and Maximum Likelihood analyzes was the same, with all the genera of Catasetinae being monophyletic and well supported. The genus Catasetum is monophyletic, however the low polymorphism found did not allow for a separation with some support of infrageneric clades. Even when using the ITS and ETS nuclear spacer, the plastid spacers trnh-psba, trns-trng, and two portions of the ycf1 gene and morphological data in our analyzes, it was not possible to obtain delimitations of the species, nor to delimit with statistical support the division into sections and subsections, since the groupings of species obtained do not correspond to the proposed infrageneric divisions.