The floral scent of Cyathostegia mathewsii (Leguminosae, Papilionoideae) and preliminary observations on reproductive biology

The chemical composition of the floral scent of two populations of Cyathostegia mathewsii (Benth.) Schery (Leguminosae, Papilionoideae, Swartzieae) were studied to test if the species is wind pollinated (as is reported for its close relative Ateleia herbert-smithii Pittier), beetle pollinated, or possesses a mixed pollination syndrome. Studies of flower visitors suggest that at night, the species might be pollinated by beetles. Only one species of beetle (Phyllophaga sp., Scarabaeidae, Melolonthinae) was caught on all individuals observed. Floral scent, collected in situ with headspace methods from flowers of three individuals of C. mathewsii, mainly contained unsaturated fatty acid derivatives, including heptadecene, and oxygenated monoterpenes, such as linalool and its oxides, as well as minor amounts of benzenoid compounds and sesquiterpenes. The composition of the scent does not preclude beetles as one of the pollinators of C. mathewsii, but it does not point towards beetles as the sole pollinators. Beetle pollination has previously only been reported from one other legume genus, Acacia (Bernhardt, 1989; Hawkeswood, 1983, 1989; Tybirk, 1993). This paper represents a second legume-beetle relationship within this diverse plant family.