title: Pollination of Specklinia by nectar-feeding Drosophila: the first reported case of a deceptive syndrome employing aggregation pheromones in Orchidaceae.
abstract: OBJECTIVE
  The first documented observation of pollination in Pleurothallidinae was that of Endrés, who noticed that the 'viscid sepals' of Specklinia endotrachys were visited by a 'small fly'. Chase would later identify the visiting flies as being members of the genus Drosophila. This study documents and describes how species of the S. endotrachys complex are pollinated by different Drosophila species.
  
  
  METHODS
  Specimens of Specklinia and Drosophila were collected in the field in Costa Rica and preserved in the JBL and L herbaria. Flies were photographed, filmed and observed for several days during a 2-year period and were identified by a combination of non-invasive DNA barcoding and anatomical surveys. Tissue samples of the sepals, petals and labellum of Specklinia species were observed and documented by SEM, LM and TEM. Electroantennogram experiments were carried out on Drosophila hydei using the known aggregation pheromones ethyl tiglate, methyl tiglate and isopropyl tiglate. Floral compounds were analysed by gas chromatography-mass spectometry using those same pheromones as standards.
  
  
  RESULTS
  Flowers of S. endotrachys, S. pfavii, S. remotiflora and S. spectabilis are visited and pollinated by several different but closely related Drosophila species. The flies are arrested by aggregation pheromones, including ethyl tiglate, methyl tiglate and isopropyl tiglate, released by the flowers, and to which at least D. hydei is very sensitive. Visible nectar drops on the adaxial surface of sepals are secreted by nectar-secreting stomata, encouraging male and female Drosophila to linger on the flowers for several hours at a time. The flies frequently show courtship behaviour, occasionally copulating. Several different Drosophila species can be found on a single Specklinia species.
  
  
  CONCLUSIONS
  Species of the S. endotrachys group share a similar pollination syndrome. There seem to be no species-specific relationships between the orchids and the flies. It is not expected that Specklinia species will hybridize naturally as their populations do not overlap geographically. The combination of pheromone attraction and nectar feeding is likely to be a generalized pollination syndrome in Pleurothallidinae.
authors.affiliation: Lankester Botanical Garden, University of Costa Rica, P.O. Box 302-7050 Cartago, Costa Rica, Naturalis Biodiversity Center, Leiden, The Netherlands, adam.karremans@ucr.ac.cr.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Karremans
authors.affiliation: Lankester Botanical Garden, University of Costa Rica, P.O. Box 302-7050 Cartago, Costa Rica, Harvard University Herbaria, Cambridge, MA, USA - Marie Selby Botanical Gardens, Sarasota, FL, USA.
authors.forename: Franco
authors.initials: F
authors.lastname: Pupulin
authors.affiliation: Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA.
authors.forename: David
authors.initials: D
authors.lastname: Grimaldi
authors.affiliation: Naturalis Biodiversity Center, Leiden, The Netherlands.
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Beentjes
authors.affiliation: Naturalis Biodiversity Center, Leiden, The Netherlands.
authors.forename: Roland
authors.initials: R
authors.lastname: Butôt
authors.affiliation: Department of Pharmacology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
authors.forename: Gregorio E
authors.initials: GE
authors.lastname: Fazzi
authors.affiliation: University of Applied Sciences Leiden, Leiden, The Netherlands.
authors.forename: Karsten
authors.initials: K
authors.lastname: Kaspers
authors.affiliation: Hortus botanicus, Leiden University, Leiden, The Netherlands.
authors.forename: Jaco
authors.initials: J
authors.lastname: Kruizinga
authors.affiliation: Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, The Netherlands and.
authors.forename: Peter
authors.initials: P
authors.lastname: Roessingh
authors.affiliation: Naturalis Biodiversity Center, Leiden, The Netherlands, Hortus botanicus, Leiden University, Leiden, The Netherlands, Ecology, Evolution and Biodiversity Conservation, KU Leuven, Leuven, Belgium.
authors.forename: Erik F
authors.initials: EF
authors.lastname: Smets
authors.affiliation: Naturalis Biodiversity Center, Leiden, The Netherlands, University of Applied Sciences Leiden, Leiden, The Netherlands.
authors.forename: Barbara
authors.initials: B
authors.lastname: Gravendeel
mesh_terms: D000818:Animals; D001070:Appetitive Behavior; D004330:Drosophila / Q000502:physiology*; D005260:Female; D008297:Male; D029595:Orchidaceae / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D057048:Plant Nectar; D054817:Pollination; D013045:Species Specificity
chemical_list: D010675:Pheromones; D057048:Plant Nectar
keywords: Aggregation pheromones; Drosophila repleta group; Orchidaceae; Pleurothallidinae; Specklinia endotrachys; Specklinia pfavii; Specklinia remotiflora; Specklinia spectabilis; courtship; deceit; deceptive pollination syndrome; nectar-secreting stomata; pollination biology