Samantha Koehler

The chemistry of pollination in selected Brazilian Maxillariinae orchids: floral rewards and fragrance.

We report the chemical composition of the floral rewards and the fragrance of 10 Maxillariinae (Orchidaceae) species. The species that offer rewards (labellar secretions) are usually scentless, the rewards being collected by bees. Chemical analyses revealed that the major chemical class of compounds present in the labellar secretions are triterpenoids. The rewardless Maxillariinae flowers were usually scented, and chemical analyses of their volatiles revealed that they were composed of mono and sesquiterpenoids.

Phylogeny of the Bifrenaria (Orchidaceae) Complex Based on Morphology and Sequence Data from Nuclear rDNA Internal Transcribed Spacers (ITS) and Chloroplast trnL‐trnF Region

We investigated the monophyly and phylogenetic relationships of the genera Adipe (=Stenocoryne), Bifrenaria, Cydoniorchis, and Rudolfiella, on the basis of morphology and DNA sequence data. Sixteen species from the Bifrenaria complex and six related genera were sampled. Matrices were analyzed using maximum parsimony. Separate analyses of data partitions resulted in slightly different nonconflicting topologies; therefore, we combined all the data sets. The results support the monophyly of Bifrenaria and of Rudolfiella. Within Bifrenaria, two clades are strongly supported: the Amazonian clade and the southern Brazilian clade. Adipe is a paraphyletic group. Although Cydoniorchis is monophyletic and has many morphological synapomorphies, the acceptance of this genus would demand many nomenclatural changes. We propose recognizing a broad Bifrenaria. The results also indicate an Amazonian origin for Bifrenaria.

Brasiliorchis: A New Genus for the Maxillaria picta Alliance (Orchidaceae, Maxillariinae)

ABSTRACT Brasiliorchis R. Singer, S. Koehler & Carnevali is here proposed to include the orchid species formerly recognized in the Maxillaria picta alliance, an orchid group mostly endemic to the Atlantic Rain Forest Biome, in south and southeastern Brazil. The new genus is supported by both morphological features and ongoing molecular studies. The new genus is easily diagnosed by its sulcate to ridged, bifoliate pseudobulbs and its long-lasting, campanulate, rewardless flowers. The pollinaria of these flowers are normally devoid of stipes. Formal diagnosis of the genus and 13 taxonomic combinations are presented: Brasiliorchis barbozae (Loefgren) R. Singer, S. Koehler & Carnevali, B. chrysantha (Barbosa Rodrigues) R. Singer, S. Koehler & Carnevali, B. consanguinea (Klotzsch) R. Singer, S. Koehler & Carnevali, B. gracilis (Loddiges) R. Singer, S. Koehler & Carnevali, B. heismanniana (Barbosa Rodrigues) R. Singer, S. Koehler & Carnevali, B. kautskyi (Pabst) R. Singer, S. Koehler & Carnevali, B. marginata (Lindley) R. Singer, S. Koehler & Carnevali, B. phoenicanthera (Barbosa Rodrigues) R. Singer, S. Koehler & Carnevali, B. picta (Hooker) R. Singer, S. Koehler & Carnevali, B. polyantha (Barbosa Rodrigues) R. Singer, S. Koehler & Carnevali, B. porphyrostele (Reichenbach f.) R. Singer, S. Koehler & Carnevali, B. schunkeana (Campacci & Kautsky) R. Singer, S. Koehler & Carnevali, and B. ubatubana (Hoehne) R. Singer, S. Koehler & Carnevali. Lectotypes are designated for B. barbozae, B. chrysantha, B. heismanniana, B. phoenicanthera, B. picta, and B. polyantha. A neotype is proposed for B. consanguinea. In addition, a key to distinguish Brasiliorchis from other sympatric bifoliate orchids within Brazilian Maxillariinae is presented.

Hydrocharitaceae from central Brazilc a new species of Egerlia and a note on Apalanthe granatensis

Egeria heterostemon (Hydrocharitaceae), a new species from central Brazil, is described and illustrated. It is distinguished from congeneric species by its flowers having heteromorphic whorls of stamens, and by its long-stalked clavate staminodes, which are strongly papillose distally. Further, taxonomic notes on Apalanthe granatensis (Humboldt & Bonpland) Planchon are presented, and a key to species of both genera is provided.

Alismatales from the upper and middle Araguaia river basin (Brazil)

The present study deals with a survey of the order Alismatales (except Araceae) in the upper and middle Araguaia River region located between the states of Mato Grosso and Goias, Brazil. Field expeditions were carried out during the rainy and dry seasons. The route covered approximately 2,000 km and 41 aquatic environments were visited. Thirteen taxa, representing the families Alismataceae (nine), Hydrocharitaceae (three) and Najadaceae (one) were identified. Keys for the identification of families and species in field, brief diagnoses, schematic illustrations and relevant comments were elaborated based on field observations as well as on the analysis of the specimens collected.

A taxonomic study of the South American genus Bifrenaria Lindl. (Orchidaceae)

A taxonomic study is presented for the South American orchid genusBifrenaria Lindl., which is characterized, within the subtribe Maxillariinae, by four-angled, unifoliate pseudobulbs, plicate leaves, and by flowers bearing a conspicuous spur and a pollinarium usually with a forked stipe. We considerBifrenaria a monophyletic group includingAdipe (=Stenocoryne),Cydoniorchis, andBifrenaria sensu stricto. The main goals of this study are to present a taxonomic synopsis of genusBifrenaria, determining which taxa should be recognized, their distributions, and which characters traditionally used to discriminate species are taxonomically informative. Identification keys, descriptions, distribution maps, and line drawings are also provided.

Karyotype diversity and genome size variation in Neotropical Maxillariinae orchids

Orchidaceae is a widely distributed plant family with very diverse vegetative and floral morphology, and such variability is also reflected in their karyotypes. However, since only a low proportion of Orchidaceae has been analysed for chromosome data, greater diversity may await to be unveiled. Here we analyse both genome size (GS) and karyotype in two subtribes recently included in the broadened Maxillariinea to detect how much chromosome and GS variation there is in these groups and to evaluate which genome rearrangements are involved in the species evolution. To do so, the GS (14 species), the karyotype - based on chromosome number, heterochromatic banding and 5S and 45S rDNA localisation (18 species) - was characterised and analysed along with published data using phylogenetic approaches. The GS presented a high phylogenetic correlation and it was related to morphological groups in Bifrenaria (larger plants - higher GS). The two largest GS found among genera were caused by different mechanisms: polyploidy in Bifrenaria tyrianthina and accumulation of repetitive DNA in Scuticaria hadwenii. The chromosome number variability was caused mainly through descending dysploidy, and x=20 was estimated as the base chromosome number. Combining GS and karyotype data with molecular phylogeny, our data provide a more complete scenario of the karyotype evolution in Maxillariinae orchids, allowing us to suggest, besides dysploidy, that inversions and transposable elements as two mechanisms involved in the karyotype evolution. Such karyotype modifications could be associated with niche changes that occurred during species evolution.

Development and cross-validation of microsatellite markers for Rauvolfia weddeliana Müll.Arg. (Apocynaceae) species complex

AbstractRauvolfia weddeliana is an endemic species restricted to plateau landscapes in South American savannahs. Rapid loss of habitat and expansion of agriculture in Central-West Brazil have critically reduced the original extent of savannahs, representing a major threat to its biotic diversity. Due to the discontinuous distribution of R. weddeliana and the vulnerability of its habitats, it is crucial to estimate the genetic diversity of remaining populations. The application of microsatellite markers is a useful approach with relative low cost and high informative potential for studies related to conservation genetics and population genetics. The development of specific libraries for endangered species may aid future studies about the connectivity of populations, reproductive biology, and genetic diversity. We developed microsatellite markers for R. weddeliana and tested the transferability of the markers to a closely related species, R. gracilis. Ten microsatellite markers were identified, and a set of primers for their amplification is presented. Most identified motifs were dimers, with lengths from 18 to 74 base pairs. Nine markers presented high informative potential (PIC > 0.5). The set of markers developed in this study will support further investigations in population genetics of R. weddeliana and possibility of closely related species.