Papers by Samantha Koehler
Alismatales from the upper and middle Araguaia river basin (Brazil)). The present study deals wit... more 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 Goiás, 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.
† Background and Aims Species' boundaries applied within Christensonella have varied due to the c... more † Background and Aims Species' boundaries applied within Christensonella have varied due to the continuous pattern of variation and mosaic distribution of diagnostic characters. The main goals of this study were to revise the species' delimitation and propose a more stable classification for this genus. In order to achieve these aims phylogenetic relationships were inferred using DNA sequence data and cytological diversity within Christensonella was examined based on chromosome counts and heterochromatin patterns. The results presented describe sets of diagnostic morphological characters that can be used for species' identification. † Methods Phylogenetic studies were based on sequence data of nuclear and plastid regions, analysed using maximum parsimony and maximum likelihood criteria. Cytogenetic observations of mitotic cells were conducted using CMA and DAPI fluorochromes. † Key Results Six of 21 currently accepted species were recovered. The results also support recognition of the 'C. pumila' clade as a single species. Molecular phylogenetic relationships within the 'C. acicularis -C. madida' and 'C. ferdinandiana-C. neowiedii' species' complexes were not resolved and require further study. Deeper relationships were incongruent between plastid and nuclear trees, but with no strong bootstrap support for either, except for the position of C. vernicosa. Cytogenetic data indicated chromosome numbers of 2n ¼ 36, 38 and 76, and with substantial variation in the presence and location of CMA/DAPI heterochromatin bands. † Conclusions The recognition of ten species of Christensonella is proposed according to the molecular and cytogenetic patterns observed. In addition, diagnostic morphological characters are presented for each recognized species. Banding patterns and chromosome counts suggest the occurrence of centric fusion/fission events, especially for C. ferdinandiana. The results suggest that 2n ¼ 36 karyotypes evolved from 2n ¼ 38 through descendent dysploidy. Patterns of heterochromatin distribution and other karyotypic data proved to be a valuable source of information to understand evolutionary patterns within Maxillariinae orchids.
Journal of Chemical Ecology, 2004
We report the chemical composition of the floral rewards and the fragrance of 10 Maxillariinae (O... more 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.
American Journal of Botany, 2007
The orchid genus Maxillaria is one of the largest and most common of neotropical orchid genera, b... more The orchid genus Maxillaria is one of the largest and most common of neotropical orchid genera, but its current generic boundaries and relationships have long been regarded as artificial. Phylogenetic relationships within subtribe Maxillariinae sensu Dressler (1993) with emphasis on Maxillaria s.l. were inferred using parsimony analyses of individual and combined DNA sequence data. We analyzed a combined matrix of nrITS DNA, the plastid matK gene and flanking trnK intron, and the plastid atpB-rbcL intergenic spacer for 619 individuals representing ca. 354 species. The plastid rpoC1 gene (ca. 2600 bp) was sequenced for 84 selected species and combined in a more limited analysis with the other data sets to provide greater resolution. In a wellresolved, supported consensus, most clades were present in more than one individual analysis. All the currently recognized minor genera of ''core'' Maxillariinae (Anthosiphon, Chrysocycnis, Cryptocentrum, Cyrtidiorchis, Mormolyca, Pityphyllum, and Trigonidium) are embedded within a polyphyletic Maxillaria s.l. Our results support the recognition of a more restricted Maxillaria, of some previously published segregate genera (Brasiliorchis, Camaridium, Christensonella, Heterotaxis, Ornithidium, Sauvetrea), and of several novel clades at the generic level. These revised monophyletic generic concepts should minimize further nomenclatural changes, encourage monographic studies, and facilitate more focused analyses of character evolution within Maxillariinae.
International Journal of Plant Sciences, 2002
We investigated the monophyly and phylogenetic relationships of the genera Adipe (pStenocoryne), ... more We investigated the monophyly and phylogenetic relationships of the genera Adipe (pStenocoryne), 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.
The orchid genus Maxillaria is one of the largest and most common of neotropical orchid genera, b... more The orchid genus Maxillaria is one of the largest and most common of neotropical orchid genera, but its current generic boundaries and relationships have long been regarded as artificial. Phylogenetic relationships within subtribe Maxillariinae sensu Dressler (1993) with emphasis on Maxillaria s.l. were inferred using parsimony analyses of individual and combined DNA sequence data. We analyzed a combined matrix of nrITS DNA, the plastid matK gene and flanking trnK intron, and the plastid atpB-rbcL intergenic spacer for 619 individuals representing ca. 354 species. The plastid rpoC1 gene (ca. 2600 bp) was sequenced for 84 selected species and combined in a more limited analysis with the other data sets to provide greater resolution. In a wellresolved, supported consensus, most clades were present in more than one individual analysis. All the currently recognized minor genera of ''core'' Maxillariinae (Anthosiphon, Chrysocycnis, Cryptocentrum, Cyrtidiorchis, Mormolyca, Pityphyllum, and Trigonidium) are embedded within a polyphyletic Maxillaria s.l. Our results support the recognition of a more restricted Maxillaria, of some previously published segregate genera (Brasiliorchis, Camaridium, Christensonella, Heterotaxis, Ornithidium, Sauvetrea), and of several novel clades at the generic level. These revised monophyletic generic concepts should minimize further nomenclatural changes, encourage monographic studies, and facilitate more focused analyses of character evolution within Maxillariinae.
Novon, 2007
Brasiliorchis R. Singer, S. Koehler & Carnevali is here proposed to include the orchid species fo... more 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. A neotype is proposed for B. consanguinea. In addition, a key to distinguish Brasiliorchis from other sympatric bifoliate orchids within Brazilian Maxillariinae is presented. RESUMO . O gênero Brasiliorchis R. Singer, S. Koehler & Carnevali, é proposto para conter aquelas espécies de orquídeas antes incluidas na Aliança Maxillaria picta; um agrupamento primariamente endêmico do bioma Mata Atlântica, no Sul e Sudeste do Brasil. Este novo gênero é sustentado tanto por caracteres morfológicos quanto por estudos de biologia molecular em andamento. O novo gênero é facilmente diagnosticado pelos seus pseudobulbos bifoliados, sulcados a canaliculados e pelas suas flores campanuladas, duradouras e sem recompensas florais. Os polinários destas espécies normalmente carecem de estipes. Apresenta-se a diagnose formal do novo gênero, bem como treze novas combinaçoes taxonômicas: Brasiliorchis barbozae (Loefgren) R. NOVON 17: 91-99. PUBLISHED ON 23 APRIL 2007.
A recent phylogenetic analysis of four DNA regions for ca. 354 species of core Maxillariinae stro... more A recent phylogenetic analysis of four DNA regions for ca. 354 species of core Maxillariinae strongly indicate that the genus Maxillaria, as traditionally circumscribed, is grossly polyphyletic. We present a new phylogenetic classification for core Maxillariinae that recognizes 17 genera. Necessary realignments include: 1) resurrection of the genera Camaridium, Heterotaxis, and Ornithidium; 2) recognition of the recent segregates Brasiliorchis (=Maxillaria sect. Repentes), Christensonella (=Maxillaria sect. Urceolatae), Nitidobulbon (in press), and a recircumscribed Sauvetrea (=Maxillaria sect. Trigonae); 3) adoption of the new genera Inti (=Maxillaria sect. Polyphyllae), Mapinguari, Maxillariella (=Maxillaria sections Ebulbes and Erectae), and Rhetinantha; 4) transfers from Maxillaria sect. Reflexae to Ornithidium, and Maxillaria sect. Rufescens to Mormolyca; and 5) synonymizing of the genera Adamanthus, Pseudomaxillaria, Psittacoglossum, and Sepalosaccus (under Camaridium), Anthosiphon (under Cryptocentrum), Chrysocycnis (under Mormolyca), Dicrypta, Marsupiaria, and Pentulops (under Heterotaxis), and Laricorchis, Neo-urbania, and Siagonanthus (under Ornithidium). Some new synonyms at the specific level are also presented.
Brittonia, 2004
A taxonomic study is presented for the South American orchid genusBifrenaria Lindl., which is cha... more 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.
Journal of Plant Research, 2003
The pollination biology of Notylia nemorosa was elucidated from field and ex situ observations. F... more The pollination biology of Notylia nemorosa was elucidated from field and ex situ observations. Field observations were carried out in Minas Gerais, southeastern Brazil, where this orchid is pollinated by males of Eulaema nigrita (Euglossini). Plants cultivated in Campinas (São Paulo State, southeastern Brazil) were eventually pollinated by males of Eulaema nigrita and Euglossa melanothricha (Euglossini). In both cases, Euglossini males collect aromatic compounds produced on the surface of the lip, fix the pollinaria on the dorsal surface of the labrum and perform pollination. This species is protandrous. Recently opened flowers present their stigmatic surfaces blocked and thus flowers act only as pollen donors. After 2–3 days the viscidium dries out and pollinaria cannot be removed anymore. Then, a narrow slit opens in the stigmatic cavity, allowing pollen deposition. Experiments performed with cultivated plants suggest that this orchid species is strongly, though not completely self-incompatible. Pollination experiments showed that bees tend to stay several minutes in each inflorescence. This behavior may promote some degree of geitonogamous pollination because flowers in male and female phases coexist in the same inflorescence. The combination of self-incompatibility with this specific pollinator behavior may explain the rarity of fruits in several neotropical reward-offering Orchidaceae.
Annals of Botany, 2008
† Background and Aims Species' boundaries applied within Christensonella have varied due to the c... more † Background and Aims Species' boundaries applied within Christensonella have varied due to the continuous pattern of variation and mosaic distribution of diagnostic characters. The main goals of this study were to revise the species' delimitation and propose a more stable classification for this genus. In order to achieve these aims phylogenetic relationships were inferred using DNA sequence data and cytological diversity within Christensonella was examined based on chromosome counts and heterochromatin patterns. The results presented describe sets of diagnostic morphological characters that can be used for species' identification. † Methods Phylogenetic studies were based on sequence data of nuclear and plastid regions, analysed using maximum parsimony and maximum likelihood criteria. Cytogenetic observations of mitotic cells were conducted using CMA and DAPI fluorochromes. † Key Results Six of 21 currently accepted species were recovered. The results also support recognition of the 'C. pumila' clade as a single species. Molecular phylogenetic relationships within the 'C. acicularis -C. madida' and 'C. ferdinandiana-C. neowiedii' species' complexes were not resolved and require further study. Deeper relationships were incongruent between plastid and nuclear trees, but with no strong bootstrap support for either, except for the position of C. vernicosa. Cytogenetic data indicated chromosome numbers of 2n ¼ 36, 38 and 76, and with substantial variation in the presence and location of CMA/DAPI heterochromatin bands. † Conclusions The recognition of ten species of Christensonella is proposed according to the molecular and cytogenetic patterns observed. In addition, diagnostic morphological characters are presented for each recognized species. Banding patterns and chromosome counts suggest the occurrence of centric fusion/fission events, especially for C. ferdinandiana. The results suggest that 2n ¼ 36 karyotypes evolved from 2n ¼ 38 through descendent dysploidy. Patterns of heterochromatin distribution and other karyotypic data proved to be a valuable source of information to understand evolutionary patterns within Maxillariinae orchids.
Plant Systematics and Evolution, 2009
Epidendrum L. is the largest genus of Orchidaceae in the Neotropical region; it has an impressive... more Epidendrum L. is the largest genus of Orchidaceae in the Neotropical region; it has an impressive morphological diversification, which imposes difficulties in delimitation of both infrageneric and interspecific boundaries. In this study, we review infrageneric boundaries within the subgenus Amphiglottium and try to contribute to the understanding of morphological diversification and taxa delimitation within this group. We tested the monophyly of the subgenus Amphiglottium sect. Amphiglottium, expanding previous phylogenetic investigations and reevaluated previous infrageneric classifications proposed. Sequence data from the trnL-trnF region were analyzed with both parsimony and maximum likelihood criteria. AFLP markers were also obtained and analyzed with phylogenetic and principal coordinate analyses. Additionally, we obtained chromosome numbers for representative species within the group. The results strengthen the monophyly of the subgenus Amphiglottium but do not support the current classification system proposed by previous authors. Only section Tuberculata comprises a well-supported monophyletic group, with sections Carinata and Integra not supported. Instead of morphology, biogeographical and ecological patterns are reflected in the phylogenetic signal in this group. This study also confirms the large variability of chromosome numbers for the subgenus Amphiglottium (numbers ranging from 2n = 24 to 2n = 240), suggesting that polyploidy and hybridization are probably important mechanisms of speciation within the group.
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Papers by Samantha Koehler