Abstract:Species interactions have been recently depicted as networks, in which each species is connected to one or more other species in binary interaction matrices. Forty networks of epiphytic orchid and host tree species were assessed in Brazilian gallery forests. The nestedness of the networks was estimated with the NODF index and the significance was tested with null models. The phylogenetic structure of the network was also assessed, by searching for phylogenetic signals in the number of interactions and in the similarity of interacting species. In total, 105 orchid species and 132 host tree species were sampled. A nested pattern in all orchid–host tree networks was found. However, phylogenetic signals were not observed. The results support that the host specificity of orchids is small and most of the interactions occur among generalist orchids and generalist host trees. While the concept of species-specificity can thus be rejected, the extreme alternative – that interacting orchids and host trees are not a random subset of the regional species pool – can be dismissed as well. However, factors other than phylogenetic history may structure interaction networks of epiphytic orchids and host trees.

ResumoEste estudo apresenta o levantamento florístico de Orchidaceae ocorrentes em 125 fragmentos florestais de 23 municípios da região central do estado de São Paulo. Foram identificadas 218 espécies distribuídas em 96 gêneros. Os indivíduos coletados em estado vegetativo foram mantidos em casa de vegetação até a ocorrência de floração. A maioria das espécies (64%) é epífita, 35% são terrícolas, 14,6% são rupícolas, duas são hemiepífitas (0,9%) e apenas uma é micoheterotrófica (0,4%). Os gêneros mais representativos são Acianthera (13 spp.), Habenaria e Gomesa (12 spp.) e Epidendrum (11 spp.). Dentre as espécies não identificadas, quatro parecem ser novas para a ciência: Anathallis sp., Baskervilla sp., Pelexia sp., Triphora sp. Além disso, uma nova combinação para o gênero Gomesa R.Br. é apresentada. O elevado número de espécies encontradas provavelmente está relacionado ao fato da região ser um ecótono entre o Cerrado e a Floresta Atlântica. Muitas das espécies (44,7%) são raras na região e encontram-se ameaçadas devido ao intenso desmatamento e coletas indiscriminadas. Palavras-chave: Cerrado, ecótono, Floresta Atlântica, levantamento florístico. AbstractThis study reports the floristic survey of Orchidaceae occurring in 125 forest fragments distributed among 23 counties of the central region of São Paulo state, Brazil. In this region, the family is characterized by 219 species distributed in 96 genera. Individuals collected in the vegetative state were maintained in a greenhouse until 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 and Gomesa (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 new combination for the genus Gomesa R.Br. is presented. The central portion of São Paulo state is an ecotone between Brazilian Savanna and Atlantic Forest with a high number of species from both formations. Many species (44.7%) are rare in the study area and are threatened due to anthropogenic disturbance and indiscriminate collecting of orchids.

Pollination of the pantropical Vanilla has been linked to melittophily and food deception.• Here we investigated the role of flower traits on the reproduction of Neotropical Vanilla. We also studied the evolution of pollination systems in order to understand the origin of production of flower resources and the diversification of pollinators in this orchid genus. Our study was founded on data of adaptations in flower morphology, production of resources, scent release, pollinators and breeding systems of Vanilla and presenting new data on reproductive biology of V. palmarum. Data on reproductive biology of Vanilla were mapped onto a phylogeny to address our queries on the evolution of pollination systems in this genus.• Vanilla palmarum shows a mixed mating system, with its facultative autogamous flowers being pollinated by hummingbirds. Its yellow flowers are scentless and produces nectar. Mapping of the pollination system onto trees resulted in one origin for bird pollination and at least two origins for autogamy in Vanilla. Nectar secretion has a single origin in the Neotropical thick-leafed lineage.• Bird pollination of Vanilla is shown for the first time. The origin of ornithophily within a bee-pollinated clade is supported by flower morphology. Floral transitions to ornithophily have been favoured by the occupation of a distinct niche from that of the other thick-leafed Vanilla species. Despite its specialized pollination, V. palmarum is autogamous. A mixed mating system can promote reproductive assurance in the case of a decline in pollinator populations, or in areas where pollinator services are irregular or absent.

We present here the first records of Vanilla bahiana and Vanilla pompona from Maranhão state, northeastern Brazil. Both species were collected in a gallery forest, in areas of Cerrado vegetation at Caxias municipality. This work contributes with knowledge on the geographical distribution of the species in northeastern Brazil.

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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.

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This study reports the first record of Passiflora pedata L. (Passifloraceae) from the state of Maranhão and from the Northeast Region of Brazil. The species was collected in the municipality of Buriticupu, which is located in a remnant of Amazon Forest in western Maranhão. This work adds to the knowledge of the flora of Maranhão and the distribution of P. pedata in the Brazilian Amazon.