Emerson R. Pansarin

Reproductive biology of Cyrtopodium polyphyllum (Orchidaceae): a Cyrtopodiinae pollinated by deceit.

The genus Cyrtopodium comprises about 42 species distributed from southern Florida to northern Argentina. Cyrtopodium polyphyllum occurs on rocks or in sandy soils, in restinga vegetation along the Brazilian coast. It flowers during the wet season and its inflorescences produce a high number of resupinate yellow flowers. Cyrtopodium polyphyllum offers no rewards to its pollinators, but mimics the yellow, reward-producing flowers of nearby growing Stigmaphyllon arenicola (oil) and Crotalaria vitellina (nectar) individuals. Several species of bee visit flowers of C. polyphyllum, but only two species of Centris (Centris tarsata and Centris labrosa) act as pollinators. Visits to flowers of C. polyphyllum were scarce and, as a consequence, low-fruit set was recorded under natural conditions. Such low-fruit production contrasts with the number of fruits each plant bears after manual pollination, suggesting deficient pollen transfer among plants. C. polyphyllum is self-compatible and has a high-fruit set in both manual self- and cross-pollinated flowers. Furthermore, fruits (2%) are formed by self-pollination assisted by rain. This facultative self-pollination mechanism is an important strategy to provide reproductive assurance to C. polyphyllum as rainfall restricts the foraging activity of its pollinating bees. Fruits derived from treatments and under natural conditions had a similar high rate of potentially viable seed. Moreover, these seeds had a low polyembryony rate, which did not exceed 5%. C. polyphyllum acts by deceit involving optical signals and exploits other yellow-flowered species within its habitat by attracting their pollinators. The low capsule production under natural conditions was expected, but its reproductive success is assured through self-pollination by rain and high seed viability.

Orchidaceae na região central de São Paulo, Brasil

Abstract This study reports the floristic survey of Orchidaceae occurring in 125 forest fragments distributed among 23counties of the central region of Sao Paulo state, Brazil. In this region, the family is characterized by 219species distributed in 96 genera. Individuals collected in the vegetative state were maintained in a greenhouseuntil flowering. The majority of species (64%) are epiphytes, while 35% are terrestrial, 14.6% are rupicolous,two (0.9%) are hemi-epiphytes and one is mycoheterotrophic (0.4%). Acianthera (13 spp.), Habenaria andGomesa (12 spp.), and Epidendrum (11 spp.) are the most representative genera. Of the unidentified species,four are possibly new to science: Anathallis sp., Baskervilla sp., Pelexia sp., Triphora sp. Furthermore, a newcombination for the genus Gomesa R.Br. is presented. The central portion of Sao Paulo state is an ecotonebetween Brazilian Savanna and Atlantic Forest with a high number of species from both formations. Manyspecies (44.7%) are rare in the study area and are threatened due to anthropogenic disturbance and indiscriminatecollecting of orchids.Key words: Savanna, ecotone, Atlantic Forest, floristic survey.

Floral biology and histochemical analysis of Vanilla edwallii Hoehne (Orchidaceae: Vanilloideae): an orchid pollinated by Epicharis (Apidae: Centridini)

The genus Vanilla is the most diverse in Vanilloideae, with ca 90 species distributed among tropical regions. Despite their economic importance, studies on pollination of Vanilla are very scarce and data on pollinators of species endemic to Brazil are lacking. Based on fieldwork and laboratory investigations, the floral biology of V. edwallii was studied. The pollinators and pollination process were recorded at the Serra do Japi reserve, state of Sao Paulo, southeastern Brazil, and the presence of floral reward was also investigated. Vanilla edwallii blooms in summer. The lateral inflorescences produce up to four pale green flowers. The white labellum is united to the base of the column forming a mentum. In the studied population V. edwallii is pollinated by Epicharis (Hoplepicharis) affinis, where the males exhibit a territorial behavior, defending flowers from other possible flower visitors. The pollen is deposited on the scutellum of bees when they abandon the flower. The mentum region is dry, suggesting no nectar production. The only secretory structures are osmophores dispersed on the inner surface of the lip responsible for production of a sweet fragrance, which together with color and morphology of flowers is related to bee attraction. The labellum is rich in mucilaginous cells, while the mucilaginous substance is retained inside the cells. The histochemical analysis also detected the presence of phenolic compounds and starch concentrated mainly at the adaxial surface of the lip and around the vascular bundles.

Reproductive biology of Epidendrum tridactylum (Orchidaceae: Epidendroideae): a reward-producing species and its deceptive flowers

Epidendrum L. (Epidendroideae, Laeliinae) is one of the largest orchid genera distributed throughout tropical America. Based on data on reproductive phenology, floral morphology, labellar histochemistry, pollinators, pollination mechanisms and breeding system, this study explored the reproductive biology of Epidendrum tridactylum Lindl. growing in the state of São Paulo, southeastern Brazil. Epidendrum tridactylum produces an average of 87 rewardless flowers with a longitudinal protuberance on the median portion of its labellum, whose epidermal cells produce a pleasant citric fragrance. This fragrance attracts both male and female flies of families Calliphoridae, Sarcophagidae and Syrphidae that end up drinking the extrafloral nectar produced at the base of the bracts. Pollinaria are removed when the fly proboscis contacts the viscidium in search of nectar. After removing the pollinarium, the fly gets trapped in the flower, which frightens it, thus inhibiting any possible intent to immediately visit another flower and, at least presumably, reducing the possibility of geitonogamy. Since E. tridactylum is self-incompatible, the positive consequence of such behavior is a reduction of pollen loss. The fruits obtained through experimental cross-pollinations present highly variable percentages of potentially viable seeds. This is the first comprehensive study on the reproductive biology of a myophilous Epidendrum and a pioneer report of effective pollinators picking extrafloral nectar from Orchidaceae.

Facultative autogamy in Cyrtopodium polyphyllum (Orchidaceae) through a rain-assisted pollination mechanism

Cyrtopodium includes ~42 species, among which is Cyrtopodium polyphyllum (Vell.) Pabst ex F. Barros that occurs in a rainforest in south-eastern Brazil. Its non-rewarding flowers, which attract Centridini bees by deceit, are rain-assisted self-pollinated, a phenomenon rarely found in orchids and other plant families. In addition, self-pollination has never been reported in Cyrtopodiinae and data on the pollination of South American orchids are scarce. Flowers were observed at different times of the day, on both sunny and rainy days, to record floral morphology, visitors and the effects of rainfall on flowers. On rainy days, water accumulates on the stigma and dissolves the adhesive substance of the stigmatic surface. A viscous drop thus forms, which contacts the pollinarium. When evaporation makes the viscous drop shrink, the drop moves the pollinarium with the anther onto the stigmatic surface and promotes self-pollination. Fruit set in natural habitat was low, with 2.4% at one study site, where a similar value (2.2%) was recorded in flowers self-pollinated by rain. In C. polyphyllum, facultative self-pollination assisted by rain is thus an important strategy that guarantees fruit set when pollinator’s visits are scarce, which is common in species pollinated by deceit.

Andean Mountain Building Did not Preclude Dispersal of Lowland Epiphytic Orchids in the Neotropics

The Andean uplift is one of the major orographic events in the New World and has impacted considerably the diversification of numerous Neotropical lineages. Despite its importance for biogeography, the specific role of mountain ranges as a dispersal barrier between South and Central American lowland plant lineages is still poorly understood. The swan orchids (Cycnoches) comprise ca 34 epiphytic species distributed in lowland and pre-montane forests of Central and South America. Here, we study the historical biogeography of Cycnoches to better understand the impact of the Andean uplift on the diversification of Neotropical lowland plant lineages. Using novel molecular sequences (five nuclear and plastid regions) and twelve biogeographic models, we infer that the most recent common ancestor of Cycnoches originated in Amazonia ca 5 Mya. The first colonization of Central America occurred from a direct migration event from Amazonia, and multiple bidirectional trans-Andean migrations between Amazonia and Central America took place subsequently. Notably, these rare biological exchanges occurred well after major mountain building periods. The Andes have limited plant migration, yet it has seldom allowed episodic gene exchange of lowland epiphyte lineages such as orchids with great potential for effortless dispersal because of the very light, anemochorous seeds.

Taxonomic notes on Pogonieae (Orchidaceae): Cleistesiopsis, a new genus segregated from Cleistes, and description of two new South American species, Cleistes batistana and C. elongata

SummaryA new genus, Cleistesiopsis, was segregated from Cleistes based on morphological and molecular characteristics, and two new species of Cleistes: C. batistana and C. elongata, both occurring in the Brazilian Central Plateau (Central-Western Brazil), are described and illustrated. Furthermore, a key to genera currently recognised within Pogonieae is presented.ResumoUm novo gênero, Cleistesiopsis, é segregado de Cleistes com base em caracteres morfológicos e moleculares, e duas novas espécies de Cleistes: C. batistana e C. elongata, que ocorrem no Planalto Central, no Centro-Oeste do Brasil, são descritas e ilustradas. Além disso, uma chave para os gêneros que atualmente compõem a tribo Pogonieae é apresentada.

Butterfly pollination in Pteroglossa (Orchidaceae, Orchidoideae) : a comparative study on the reproductive biology of two species of a Neotropical genus of Spiranthinae

Spiranthinae orchids are known for being self-compatible and offering nectar as a reward. Although data on their pollinators are scarce, members of this tribe are mostly pollinated by bees, hummingbirds and moths. Some of them even reproduce through facultative self-pollination. Nothing is known about the pollinators and reproduction system in Pteroglossa. Based on records on flowering phenology, floral morphology, reward production, pollinators and breeding system, this paper aims to study the reproductive biology of two Pteroglossa spp. Both species offer nectar as a resource and are pollinated exclusively by diurnal Lepidoptera at the studied areas. Nectar is produced by two glandular nectaries, and is stored in a spur. Pollinaria possess a ventrally adhesive viscidium that is deposited on the basal portion of butterfly proboscides. Both species are self-compatible but pollinator-dependent. The reproductive success is low when compared to other Spiranthinae. Although no evident mechanical barrier to avoid self-pollination or geitonogamy was identified, the erratic behavior of the butterflies, with their infrequent visits to only one flower per inflorescence, contributes to an increased fruit set produced through cross-pollination. The presence of ventrally adhesive viscidia in Spiranthinae is responsible for greater pollinator diversity when compared to bee-pollinated Goodyerinae with dorsally adhesive viscidia, adapted to attach to bee mouthparts.

More than euglossines: the diverse pollinators and floral scents of Zygopetalinae orchids

Floral volatile organic compounds (VOCs) play important roles in plant-pollinator interactions. We investigated the reproductive ecology and floral VOCs of Zygopetalinae orchids to understand the relationship between floral scents and pollinators. We performed focal observations, phenological censuses and breeding system experiments in eight species in southeast Brazil. Floral scents were collected and analysed using SPME/GC-MS. We performed multivariate analyses to group species according to affinities of their VOCs and define compounds associated to each plant. Dichaea cogniauxiana was pollinated by weevils which use their developing ovules, while D. pendula was pollinated by the same weevils and perfume-collecting male euglossine bees. The other species were deceit-pollinated by bees. Zygopetalum crinitum was pollinated by carpenter bees, while W. warreana, Z. mackayi and Z. maxillare were bumblebee-pollinated. The latter was also pollinated by Centris confusa. Breeding system varied widely with no association to any pollinator group. Most VOCs are common to other floral scents. Zygopetalum crinitum presented an exclusive blend of VOCs, mainly composed of benzenoids. The scents of Pabstia jugosa, Promenaea xanthina and the Zygopetalum spp. were similar. The bumblebee-pollinated species have flowering periods partially overlapped, thus neither phenology nor pollinators constitute hybridization barriers among these species. Euglossines are not the only pollinators of Zygopetalinae. Different VOCs, size and lifespan of flowers are associated with distinct pollinators. A distinctive VOC bouquet may determine specialisation in carpenter bees or male euglossines within bee-pollinated flowers. Finally, visitation of deceit-pollinated flowers by perfume-collecting euglossines allows us to hypothesise how pollination by this group of bees had evolved.

Genetic variability within and among populations of an invasive, exotic orchid

Originally from Africa, the terrestrial orchid Oeceoclades maculata, considered an invasive plant, is the only species of the genus throughout the Americas. We used 13 ISSR primers to assess the genetic diversity and structure of 152 individuals of O. maculata distributed in five sampled sites in Brazil. Low diversity was found within samples while most of the genetic diversity was found among localities. A substructure was observed in one of the sites, suggesting lack of gene flow even between very small distances. Results may be understood considering the interaction between the reproductive system, colonization history, genetic drift, selective pressures and multiple introductions.