Delimitação e evolução de bambus herbáceos da linhagem Olyrinae (Poaceae-Bambusaideae-Olyreae), com ênfase nos gêneros Raddiella Swallen e Parodiolyra Soderstr & Zuloaga

Abstract

The genera Raddiella Swallen and Parodiolyra Soderstr. & Zuloaga belong to the tribe Olyreae, subtribe Olyrinae, a group of Neotropical Poaceae including herbaceous bamboos. This is typical forest tribe with great ecological importance and poorly explored ornamental potential. Molecular phylogeny studies based on nuclear and cp-DNA spacers indicate that Parodiolyra and Raddiella are components of one of the most well supported lineages in Olyrinae, with Diandrolyra Stapf as sister group. However, the inner relationships in this lineage remain uncertain, due to the scarcity of studies involving the group. The use of DNA sequences has been efficient to comprehend the evolutionary relationships and the limits among bamboos groups. In this way, the aim of this study was to expand the knowledge about the biodiversity and evolution of the tribe by clarifying the phylogenetic relationships among Parodiolyra and Raddiella. The sampling of these genera were amplified and sequences of different regions of nuclear genome (ITS1-5.8S-ITS2) and cpDNA (rpl32-trnL, trnD-trnT, trnS-trnG and ndhF) were generated and the data was analyzed by Maximum Parsimony (MP), Bayesian Inference (BI) and Maximum Likelihood (ML) methods. The results obtained reinforced that Olyrinae and Parianinae are monophyletic and the paraphyly of Olyra L. and Sucrea Soderstr. Diandrolyra was confirmed as sister group of Parodiolyra-Raddiella clade, which has P. micrantha (Kunth) Davidse & Zuloaga as sister of the clade formed by the other species of Parodiolyra and Raddiella. This species is here transferred to the proposed new genus, Taquara I.L.C.Oliveira & R.P.Oliveira and in this context Parodiolyra becomes monophyletic. The inner results in Raddiella were incongruent by reason of the position of R. malmeana Zuloaga & Judz, recovered as sister group of Parodiolyra species, except for rpl32 and ITS. The delimitation of Raddiella continue uncertain due to the incongruences and the low sampling of phreatophytes species. The work contributes to the understanding of herbaceous bamboos evolution and increases the knowledge of the diversity of Brazilian flora throughout the description of a new genus. It also provides an important base to posterior studies, for applied purposes as well as conservative, once the majority of Olyreae species are endangered to extinction.