A Semivolatile Floral Scent Marks the Shift to a Novel Pollination System in Bromeliads.

Perfume flowers (sensu Vogel1) produce intense scents that function both as attractants and as the sole rewards for pollinators. The scent is collected exclusively by male euglossine bees and used during pre-mating behavior.2-5 Perfume flowers have evolved independently in 15 angiosperm families, with over 1,000 reported species across the Neotropical region.6 Members of Cryptanthus (Bromeliaceae) represent a puzzling exception among perfume flowers, as flowers produce nectar and do not emit a noticeable scent yet still attract euglossine males.7 Here, we studied the pollination ecology of Cryptanthus burle-marxii and decode the chemical communication between its flowers and euglossine males. Field observations revealed euglossine males and hummingbirds as potential pollinators. The bees always contacted anthers/stigma of C. burle-marxii while scraping the petals to obtain chemicals, whereas nectar-seeking hummingbirds normally only contacted the anthers. Based on gas chromatography-mass spectrometry/nuclear magnetic resonance analyses of flower scent samples and bioassays, we identified the diterpene copalol as the only floral scent compound triggering scent-gathering behavior in euglossine males. Unlike euglossine-bee-mediated pollination, hummingbird pollination is ancestral in the Cryptanthus clade, suggesting a case of an ongoing pollinator shift8-10 mediated by the evolution of perfume as a reward. Copalol was previously unknown as a floral scent constituent and represents the heaviest and least-volatile compound known to attract euglossine males. Our study provides the first experimental evidence that semivolatile floral compounds can mediate euglossine bee interactions. Male euglossine pollination in other plant species lacking noticeable floral scents11-13 suggests that semivolatile-mediated pollinator attraction is more widespread than currently appreciated.

Unusual alkaloids of the highland species Astragalus cryptanthus Wedd. (Fabaceae).

Two unusual caprolactam alkaloids, 3-(dimethylamino)hexahydro-2H-azepin-2-one and 3-(methylamino)-hexahydro-2H-azepin-2-one, were isolated from the aerial parts of Astragalus cryptanthus Wedd.; their structures were unambiguously determined based on data from extensive 1D and 2D NMR, GC-MS and FT-IR spectroscopic analyses. This is the first report of this alkaloid type in the genus Astragalus.

Molecular phylogeny, character evolution and historical biogeography of Cryptanthus Otto & A. Dietr. (Bromeliaceae).

Cryptanthus comprises 72 species endemic to eastern Brazil with a center of diversity in the Atlantic Forest. The majority of the species are threatened due to habitat loss. We reconstructed phylogenetic relationships in Cryptanthus based on amplified fragment length polymorphisms (AFLP) including 48 species and 109 accessions. The Bayesian phylogenetic analysis revealed four major lineages in Cryptanthus and provided further evidence for the paraphyly of subgen. Hoplocryptanthus, while subgenus Cryptanthus was resolved as monophyletic. Monophyly of previously recognized morphological species groups at sectional level could not be confirmed. Based on the phylogenetic reconstruction we inferred the evolution of the sex system in Cryptanthus via maximum likelihood (ML) ancestral character reconstruction. Homoecy, the possession of hermaphrodite flowers only, was reconstructed as the ancestral state in the genus and characterizes three of the four main lineages within Cryptanthus. Andromonoecy, the possession of male and hermaphrodite flowers on the same plant, evolved only once and represents a synapomorphy of the fourth main lineage, C. subgen. Cryptanthus. The ancestral biome analysis reconstructed Cerrado (semiarid scrublands and forests) and campos rupestres (rock fields) as the most likely ancestral biomes for the genus. A shift to the Atlantic Forest biome was reconstructed to have occurred twice, in the ancestor of the first diverging lineage within the genus and in the ancestor of the C. subgen. Cryptanthus clade. A shift to the Caatinga (tropical dryland savanna) and one reversal to Cerrado (campos rupestres - rock fields) was reconstructed to have occurred once, in C. bahianus and C. arelii, respectively. The ancestral biome reconstruction indicates a high degree of niche conservatism within Cryptanthus with rare biome shifts throughout the evolution of the genus. Further, our results imply that the current infrageneric taxonomy of Cryptanthus is problematic and requires revision.

A new combination in Lapanthus (Bromeliaceae).

A new combination, Lapanthus vidaliorum (O.B.C. Ribeiro & C.C. Paula) Louzada & Wand. is proposed for Orthophytum vidaliorum O.B.C. Ribeiro & C.C. Paula. In addition notes on taxonomy, geographic distribution and conservation are provided.