We studied the reproductive biology of three sympatric Araceae species, Anthurium sagittatum, A. thrinax and Spathiphyllum humboldtii in French Guiana. The plants flowered simultaneously and were visited by scent-collecting male euglossine bees, which were apparently their major pollinators. In total, each species was visited by 3-7 euglossine species, and 2-3 euglossine species accounted for at least 80% of all flower visits, with visits being plant species-specific. Floral scent consisted of 6-10 main compounds, which made up 76-94% of the total amount of volatiles and were specific in these high amounts to each plant species. We suggest that the different floral scents lead to clear separation of the main pollinating euglossine species, providing a directed and efficient intraspecific pollen flow that results in high reproductive success. Since the simple floral (inflorescence) morphology of the studied plants does not support any morphological mechanisms to exclude visitors, as for example in euglossine-pollinated perfume orchids, floral scent might be of major importance for the reproductive isolation and sympatric occurrence of these plants.

Voyria is an old, phylogenetically isolated lineage within Gentianaceae, and the current distribution of the genus is indicative of the ancestral area in which the early diversification events of Gentianaceae occurred. In parallel with many other pantropical families, our results suggest that migration of tropical taxa through Laurasia during the Early Eocene has played an important role in shaping the current global distribution of Gentianaceae.

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This paper presents an exhaustive review of the current knowledge on pollination of Araceae genera with bisexual flowers. All available studies on floral morphology, flowering sequence, floral scent, floral thermogenesis, floral visitors, and pollinators were carefully examined, with emphasis on the species-rich genera Anthurium Schott, Monstera Adans., and Spathiphyllum Schott. Genera with bisexual flowers are among the early-diverging lineages in Araceae, but present adaptations in their floral ecology to a great variety of pollination vectors, such as bees, beetles, flies, and, unusually, wind. These clades have developed highly derived pollination systems, involving the use of floral scent as a reward. We conclude that floral scent chemistry plays a key role in the pollination biology of the plants and that, in some genera, reproductive isolation through variation in the emitted floral volatile compounds may have been the decisive factor in the speciation processes of sympatric species.

In Mexico, the mostly neotropical genus Spathiphyllum is represented by twelve species, including only one species for the state of Tabasco. A detailed review of herbarium specimens, and material collected and cultivated from different locations in Tabasco, allowed us to conclude that S. cochlearispathum does not occur in Tabasco, and that specimens from different populations identified as S. cochlearispathum correspond to two different species. Here, we describe and illustrate S. maldonadianum and S. wilfridianum, two new species from Tabasco, Mexico, one of which is critically endangered. We also provide data on the composition of the floral scent of both species and their phenology.