.

Abstract

A contribution to the pollination ecology of Tabebuia pulcherrima (Bignoniaceae) in a sandbank area of the south of Santa Catarina State, Brazil. Studies on pollination mechanisms in Bignoniaceae have shown some evidence of coevolution with its pollen vectors. Floral biology and flower visitors of Tabebuia pulcherrima were investigated in a sandbank area. Flower phenology, the nectar production, pollen/ovule ratio, and identification of the flower visitors, as well as their behavior, were studied. T pulcherrima displays typical melitophilous flowers, due to its morphology, diurnal anthesis and day-long nectar secretion. In the morning, the nectar volume is smaller, which is associated with a higher frequency of visitors. The pollen/ovule ratio indicates facultative xenogamy. We collected 88 insects on the flowers, 52% of which were bees; the rest were wasps, flies, ants and beetles. The most abundant species were Niltonia virgilii (42%), Bombus mono (20%) and Xylocopa brasilianorum (18%). According to their frequency, abundance and visiting behavior, Bombus mono and Niltonia virgilii were considered to be the potential pollinators of T pulcherrima and Epicharis dejeanii, a secondary pollinator. The carpenter bee Xylocopa brasilianorum is a nectar robber of T pulcherrima. The flowers of T pulcherrima are an important food source for the entomofauna of the restinga, offering nectar and pollen as floral rewards.