Flora das cangas da Serra dos Carajás, Pará, Brasil: Melastomataceae

Late Quaternary hydroclimate and vegetation changes in an upland lake in southeastern Amazonia

An integrated approach considering facies, isotopic, and palynological analyses of lake sediments from the Serra Norte de Carajás, southeastern Amazonia, is presented in this work to refine paleoclimate and paleohydrological changes based on upland lake sediments during the late Quaternary. The sediments have a fining-upward deposition cycle typical of upland swamps/lakes. The origin of organic matter is autochthonous mainly related to C3 terrestrial plants, macrophytes and algae. The pollen records of Hedyosmum during the Early Pleistocene suggest lower temperatures than those observed along Holocene. In the transitional period between the Pleistocene and the Holocene, rainfall decreased, causing the retraction of the flooded area, favoring the development of marshy conditions. The Late and Middle Holocene were marked by higher temperatures and lower humidity. Afterward, the increased pollen concentration from canga and forest vegetation, macrophytes, palms, and algae suggested increased humidity in the Early Holocene. The relative contribution of forest pollen along the records indicated that drier conditions were not strong enough for an extensive expansion of canga over forested areas.

The genus Justicia (Acanthaceae) in the state of Pará, Amazon, Brazil

Abstract The taxonomic knowledge for genus Justicia in the Amazonian state of Pará, Brazil, is updated. The study was based on material from important national and international herbaria, as well as specimens collected in different vegetation types within the state, some of them kept under cultivation by the first author. Twenty five species of Justicia were recorded for Pará: J. asclepiadea, J. birae, J. calycina, J. carajensis, J. cayennensis, J. comata, J. distichophylla, J. divergens, J. gendarussa, J. laevilinguis, J. mcdadeana, J. montealegrensis, J. multiglandulosa, J. oldemanii, J. oriximinensis, J. paraensis, J. pectoralis, J. polystachya, J. potamogeton, J. pseudoamazonica, J. riedeliana, J. secunda, J. sphaerosperma, J. sprucei, J. yurimaguensis. Among these, five are new records for the state of Pará (J. asclepiadea, J. cayennensis, J. gendarussa, J. oldemanii, and J. yurimaguensis). Moreover, seven of the accepted names are lectotypified and a new name (J. oriximinensis) is proposed. A species identification key is presented alongside detailed morphological descriptions (including seed analysis), distribution and habitat information, taxonomic comments and illustrations.

Unraveling the plant diversity of the Amazonian canga through DNA barcoding

The canga of the Serra dos Carajás, in Eastern Amazon, is home to a unique open plant community, harboring several endemic and rare species. Although a complete flora survey has been recently published, scarce to no genetic information is available for most plant species of the ironstone outcrops of the Serra dos Carajás. In this scenario, DNA barcoding appears as a fast and effective approach to assess the genetic diversity of the Serra dos Carajás flora, considering the growing need for robust biodiversity conservation planning in such an area with industrial mining activities. Thus, after testing eight different DNA barcode markers (matK, rbcL, rpoB, rpoC1, atpF-atpH, psbK-psbI, trnH-psbA, and ITS2), we chose rbcL and ITS2 as the most suitable markers for a broad application in the regional flora. Here we describe DNA barcodes for 1,130 specimens of 538 species, 323 genera, and 115 families of vascular plants from a highly diverse flora in the Amazon basin, with a total of 344 species being barcoded for the first time. In addition, we assessed the potential of using DNA metabarcoding of bulk samples for surveying plant diversity in the canga. Upon achieving the first comprehensive DNA barcoding effort directed to a complete flora in the Brazilian Amazon, we discuss the relevance of our results to guide future conservation measures in the Serra dos Carajás.

Range-wide neutral and adaptive genetic structure of an endemic herb from Amazonian Savannas

Conserving genetic diversity in rare and narrowly distributed endemic species is essential to maintain their evolutionary potential and minimize extinction risk under future environmental change. In this study we assess neutral and adaptive genetic structure and genetic diversity in Brasilianthus carajensis (Melastomataceae), an endemic herb from Amazonian Savannas. Using RAD sequencing we identified a total of 9365 SNPs in 150 individuals collected across the species' entire distribution range. Relying on assumption-free genetic clustering methods and environmental association tests we then compared neutral with adaptive genetic structure. We found three neutral and six adaptive genetic clusters, which could be considered management units (MU) and adaptive units (AU), respectively. Pairwise genetic differentiation (F _ST) ranged between 0.024 and 0.048, and even though effective population sizes were below 100, no significant inbreeding was found in any inferred cluster. Nearly 10 % of all analysed sequences contained loci associated with temperature and precipitation, from which only 25 sequences contained annotated proteins, with some of them being very relevant for physiological processes in plants. Our findings provide a detailed insight into genetic diversity, neutral and adaptive genetic structure in a rare endemic herb, which can help guide conservation and management actions to avoid the loss of unique genetic variation.

Cangas da Amazônia: a vegetação única de Carajás evidenciada pela lista de fanerógamas

Resumo Nas cangas da Floresta Nacional (FLONA) de Carajás e no Parque Nacional dos Campos Ferruginosos (PNCF) foram registradas 856 espécies, distribuídas em 116 famílias de fanerógamas. As famílias mais ricas foram Poaceae (86), Fabaceae (65) e Rubiaceae (46). O hábito herbáceo foi o melhor representado. Dois gêneros, 24 espécies e uma subespécie são apontadas como endêmicas das cangas da área de estudos. Na FLONA de Carajás, a Serra Norte, com maior amostragem, possui 659 espécies de fanerógamas e na Serra Sul foram registradas 545 espécies. Aproximadamente 60% das espécies documentadas na área de estudos, incluindo espécies endêmicas, não possuem registro para o PNCF. Através da lista taxonômica aqui apresentada, foi possível demonstrar considerável distinção entre as cangas da Serra dos Carajás e as do Quadrilátero Ferrífero, em Minas Gerais, apontando também pouca correspondência dessas duas listas com a canga de Corumbá, no Mato Grosso do Sul. A riqueza e singularidade da flora da região, que inclui diversas espécies endêmicas, associada à ameaça a que estão submetidos estes ambientes por atividades de mineração, apontam para a necessidade de um planejamento para conservação das espécies da flora das cangas de Carajás.