Guy R. Chiron

Riqueza e endemismo de espécies de Baptistonia (Orchidaceae), no Brasil

Species endemism and species richness are complementary concepts usually used in biodiversity evaluation. They can be useful tools for efficiently defining conservation areas. In the present study, they are applied to the Brazilian Atlantic Forest, based on an orchid group endemic to this biome, the genus Baptistonia. The study of the species richness shows one very rich area (The Serra do Castelo, ES) and six rich areas. Three of these areas show an endemism index greater than 1. Eight areas, most important for biodiversity conservation, are proposed. Hierarchical relationships of endemism between nine phytogeographical areas are evaluated based on parsimony analysis of endemicity. This analysis confirms: (a) that two important endemism centers can be recognized in the southern ecological part of the Atlantic Forest, and (b) together with the phylogenetic relationships within the genus Baptistonia, that the Serra do Castelo appears to be the diversification center of the genus.

Phylogeny and evolution of Baptistonia (Orchidaceae, Oncidiinae) based on molecular analyses, morphology and floral oil evidences

Baptistonia is endemic to the Brazilian Atlantic Forest and is made up of 23 species, the phylogenetic relationships of which are analysed here. Three plastid regions (psbA-trnH, rpoB-trnC and trnS-G) were sequenced. Using seven inter-simple sequence repeat (ISSR) markers, we scored 183 loci of ISSR dominant markers. Trees were obtained by successively using (a) maximum parsimony and Bayesian analysis of individual and combined sequence data sets, (b) neighbour joining (NJ) and Dollo parsimony of the ISSR data and (c) NJ analysis of the floral oil composition. These approaches, as well as the results of a previous morphological analysis, were combined using a supertree method, yielding clearer relationships within the genus. Various results of our study indicate that the Baptistonia species are recently radiated. B. colorata and B. venusta (previously known as Oncidium trulliferum) are confirmed as being sister to the remaining species of the genus. Four taxonomic groups are clearly inferred. The evolution of some morphological traits and floral oil composition proved to be strongly linked to the phylogeny.

Taxonomy of Cyrtochilum-alliance (Orchidaceae) in the light of molecular and morphological data

BackgroundThe generic separateness and specific composition of the orchid genus Cyrtochilum was discussed for almost two centuries. Over the years several smaller taxa were segregated from this taxon, but their separateness was recently questioned based on molecular studies outcomes. The aim of our study was to revise concepts of morphological-based generic delimitation in Cyrtochilum-alliance and to compare it with the results of genetic analysis. We used phylogenetic framework in combination with phenetical analysis to provide proposal of the generic delimitation within Cyrtochilum-alliance. Two molecular markers, ITS and matK were used to construct phylogenetic tree. A total of over 5000 herbarium specimens were included in the morphological examination and the phenetical analysis included 29 generative and vegetative characters.ResultsComparative morphology of the previously recognized genera: Buesiella, Dasyglossum, Neodryas, Rusbyella, Siederella and Trigonochilum is presented. A new species within the the latter genus is described. Fourteen new combinations are proposed. The key to the identification of the genera of the Cyrtochilum-alliance and morphological characteristics of each genus are provided.ConclusionsA total of six separated genera are recognized within Cyrtochilum-alliance. The reasons of the incompatibility between morphological differences observed within studied taxa and phylogenetic tree are argued and the taxonomic implications of such inconsistency, resulting in fragmentation or lumping of taxonomic units, are discussed.