Two new species of Microlicia D.Don (Melastomataceae, Microlicieae) from Chapada dos Veadeiros, Goiás State, Brazil.

Microlicia gracilis and Microlicia xylopodifera, endemic to Chapada dos Veadeiros, Goiás State, Brazil, are described, illustrated and the conservation status is also provided. Both species resemble Microlicia ordinata and Microlicia ramosa that are also endemic to Goiás, by having sessile leaf with serrate and ciliate margin, pedicellate flower, triangular and short sepal and dimorphic stamens with bicolorous and polysporangiate anthers. However, M. gracilis differs by the long internode (2-4 mm long), concolorous, semi-amplexicaul and lanceolate leaf, and petal acuminate at the apex. Microlicia xylopodifera differs in having a robust xylopodium, horizontal or slightly ascending leaf and a dense crown of glandular trichomes at the apex of flower bud.

ResumoMicrolicia gracilis e Microlicia xylopodifera, endêmicas da Chapada dos Veadeiros, são descritas, ilustradas e o estado de conservação fornecido. Ambas espécies se assemelham à Microlicia ordinata e Microlicia ramosa, também endêmicas de Goiás, por apresentarem folha séssil, com margem serreado-ciliada, flor pedicelada, sépala triangular, curta e estames dimórficos com anteras bicolores e poliesporangiadas. Contudo, M. gracilis diferencia-se pelo entrenó longo (2­4 m compr.), folha concolor, lanceolada e semiamplexicaule, e pétala acuminada no ápice. Microlicia xylopodifera difere por apresentar xilopódio robusto, folha horizontal ou levemente ascendente e uma coroa densa de tricomas glandulares no ápice do botão floral.

Seasonal changes of fructans in dimorphic roots of Ichthyothere terminalis (Spreng.) Blake (Asteraceae) growing in Cerrado.

Cerrado is a floristically rich savanna in Brazil, whose vegetation consists of a physiognomic mosaic, influenced by rainfall seasonality. In the dry season rainfall is substantially lower and reduces soil water supply, mainly for herbs and subshrubs. Climatic seasonal variations may well define phenological shifts and induce fluctuations of plant reserve pools. Some Cerrado native species have thickened underground organs that bear buds and store reserves, as adaptive features to enable plant survival following environmental stresses. Asteraceae species accumulate fructans in storage organs, which are not only reserve, but also protecting compounds against the effects of cold and drought. Ichthyothere terminalis is one Asteraceae species abundant in cerrado rupestre, with underground organs consisting of thickened orthogravitropic and diagravitropic roots. The objectives of this study were to analyze how abiotic environmental factors and plant phenology influence fructan dynamics in field grown plants, and verify if fructan metabolism differs in both root types for one year. I. terminalis accumulates inulin-type fructans in 10-40% of the dry mass in both root types. Fructan dynamics have similar patterns described for other Asteraceae species, exhibiting a proportional increase of polysaccharides with the senescence of the aerial organs. Multivariate analyzes showed that, as rainfall decreased, environmental factors had a stronger influence on metabolite levels than phenological shifts in both root types. Only slight differences were found in fructan dynamics between orthogravitropic and diagravitropic roots, suggesting they may have similar fructan metabolism regulation. However, these small differences may reflect distinct microclimatic conditions in both root types and also represent the influence of sink strength.

Structure and floristic relationships between Cerrado sensu stricto sites on two types of substrate in northern Cerrado, Brazil

We described and compared the floristic composition, richness, species diversity and structure of the tree-shrub component in pairs of Typical Cerrado (Cerrado Típico) and rocky outcrop Cerrado (Cerrado Rupestre) in two localities in Tocantins State. In each locality, we set up 10 plots of 20 × 50 m at a site, the Cerrado Típico and other Cerrado Rupestre, and sampled the individuals with Db30cm ≥ 5 cm. The rocky outcrop Cerrado did not present any trend towards lower richness and basal area compared to the Cerrado on deep soil. Few species occurred across the four sites and only two important species (Anacardium occidentale and Qualea parviflora) in the four vegetation structure were common to both environments assessed. Furthermore, the occurrence of habitat-specialist species of rocky outcrops and high altitudes (Mimosa claussenii, Tibouchina papyrus, Schwartzia adamantium and Wunderlichia cruelsiana) and the high dissimilarity among sites suggest that altitude is the main responsible for the floristic dissimilarity, followed by the influence of substrate type. Therefore, the information with respect to phytophysiognomy type as a parameter to select areas for conservation, by itself, does not effectively ensure biodiversity preservation, owing to the existing flora heterogeneity not only at local but also at regional scale, revealed by the floristic and structural particularity of each site.

Descrevemos e comparamos a composição florística, a riqueza, a diversidade de espécies e a estrutura do componente arbustivo-arbóreo em pares de Cerrado Típico e Cerrado Rupestre em duas localidades no Estado de Tocantins. Em cada localidade, alocamos 10 parcelas de 20 × 50 m em um sítio de Cerrado Típico e em outro de Cerrado Rupestre e amostramos os indivíduos com Db30cm ≥ 5 cm. Não identificamos tendência de que o Cerrado sobre solo raso com afloramentos rochosos tivesse riqueza e área basal inferiores ao Cerrado sobre solo profundo. Poucas espécies ocorreram nos quatro sítios e apenas duas espécies (Anacardium occidentale e Qualea parviflora) importantes para a estruturação das quatro vegetações foram comuns aos dois ambientes analisados. Aliado a isso, a ocorrência de espécies habitat-especialistas de ambientes com afloramentos rochosos e de elevadas altitudes (Mimosa claussenii, Tibouchina papyrus, Schwartzia adamantium e Wunderlichia cruelsiana) e a elevada dissimilaridade entre os sítios sugerem a altitude como principal responsável pela dissimilaridade florística, seguida pela influência do tipo de substrato. Assim, a utilização apenas da informação sobre o tipo fitofisionômico como parâmetro para escolha de áreas para conservação não garante a preservação efetiva da biodiversidade devido à heterogeneidade das floras existentes, tanto em escala local como regional, demonstrada pela particularidade florística e estrutural de cada sítio.

Phylogeography of Tibouchina papyrus (Pohl) Toledo (Melastomataceae), an endangered tree species from rocky savannas, suggests bidirectional expansion due to climate cooling in the Pleistocene.

Many endemic species present disjunct geographical distribution; therefore, they are suitable models to test hypotheses about the ecological and evolutionary mechanisms involved in the origin of disjunct distributions in these habitats. We studied the genetic structure and phylogeography of Tibouchina papyrus (Melastomataceae), endemic to rocky savannas in Central Brazil, to test hypothesis of vicariance and dispersal in the origin of the disjunct geographical distribution. We sampled 474 individuals from the three localities where the species is reported: Serra dos Pirineus, Serra Dourada, and Serra de Natividade. Analyses were based on the polymorphisms at cpDNA and on nuclear microsatellite loci. To test for vicariance and dispersal we constructed a median-joining network and performed an analysis of molecular variance (AMOVA). We also tested population bottleneck and estimated demographic parameters and time to most recent common ancestor (TMRCA) using coalescent analyses. A remarkable differentiation among populations was found. No significant effect of population expansion was detected and coalescent analyses showed a negligible gene flow among populations and an ancient coalescence time for chloroplast genome. Our results support that the disjunct distribution of T. papyrus may represent a climatic relict. With an estimated TMRCA dated from ∼836.491 ± 107.515 kyr BP (before present), we hypothesized that the disjunct distribution may be the outcome of bidirectional expansion of the geographical distribution favored by the drier and colder conditions that prevailed in much of Brazil during the Pre-Illinoian glaciation, followed by the retraction as the climate became warmer and moister.