Pollination of Cambessedesia wurdackii in Brazilian Campo Rupestre Vegetation, with Special Reference to Crepuscular Bees

Cambessedesia wurdackii Martins (Myrtales: Melastomataceae) is presumably endemic to the Chapada Diamantina, Bahia State, Brazil. A majority of the species of this family are pollinated by diurnal bees that buzz the floral anthers to collect pollen. The present work examined the interactions between C. wurdackii and visiting bees, focusing on temporal, morphological, and behavioral features, especially in regards to the crepuscular bees Megalopta sodalis (Vachal) (Hymenoptera: Halictidae) and Ptiloglossa off. dubia Moure (Hymenoptera: Colletidae). The study was undertaken in an area of campo rupestre montane savanna vegetation located in the Chapada Diamantina Mountains of Bahia State, Brazil, between August/2007 and July/2008. Flowering in C. wurdackii occurred from April through July, with a peak in May. A total of 592 visits by diurnal and crepuscular bees to the flowers of C. wurdackii were recorded, with a majority of the visits made by M. sodalis and P. dubia (92%) near sunrise and sunset. The anthers of C. wurdackii are arranged in two tiers, which favors cross pollination. The morphological, temporal and behavioral characteristics of M. sodalis and P. dubia indicated that they were potential pollinators of C. wurdackii, in spite of the fact that the colorful and showy flowers of this species are more typical of a diurnal melittophilous pollination syndrome.