Floral features, pollination biology, and breeding system of Comparettia coccinea (Orchidaceae: Oncidiinae)

In Orchidaceae, nectar offering has been reported in many unrelated groups, including Oncidiinae. Among members of Oncidiinae, pollination by hummingbirds has been recorded for Comparettia in Central America, but nothing is known for the Brazilian species. The phenology, floral morpho-anatomy, production of floral rewards, pollinators, pollination mechanisms, and breeding system of Comparettia coccinea were investigated in a nature reserve in southeastern Brazil. The reddish flowers of C. coccinea produce nectar (volume 0.5-5 μL, sugar concentration 17-28%) by two cylindrical glands located at the end of the labellum horns that can be accessed via two nectary entrances. The studied species is exclusively visited and pollinated by Nymphalidae butterflies and flower features, such as color, symmetry and morphology, support the occurrence of psychophily in C. coccinea. Pollinaria are attached to the butterfly eyes during the collection of nectar from the spur. When a butterfly visits the right nectar entrance, pollinaria are deposited on its left eye and vice versa. The species is self-compatible and depends on a biotic pollen vector to set fruits. This is the first record of effective pollination by butterflies in Oncidiinae .