Coleotrype madagascarica (Commelinaceae) : visual attraction and buzz pollination by anthophorid bees in Madagascar

Abstract:

Little is known about the pollination in the spiderwort family, Commelinaceae. One of the species endemic to Madagascar, Coleotrype madagascarica C. B. Clarke, is an extremely ostentatious plant. With visual attraction such as basally coloured apical leaves, vividly coloured petals and an astounding fuzzy spherical hair structure on the stamens. The aim of the present study was to investigate the pollination system and reveal the effective pollinator of C. madagascarica. Field studies in central Madagascar indicated that the flowers attract a number of species of pollen seeking bees and flies. The pollination of C. madagascarica relies on female bees that buzz the fuzzy bright yellow stamen filament hairs and later deposit pollen on the stigma topping the ventrally protruding hook shaped style of another flower. During a visit, the bee grabs on to the stamens and vibrate its flight muscles to eject pollen from the anthers. Anthophorid bees, especially Amegilla and Pachymelus, were the most frequent visitors and apparent pollinators.