Bat pollination of Weberocereus tunilla, an epiphytic rain forest cactus with functional flagelliflory

We studied the pollination of the epiphytic cactus Weberocereus tunilla (We ber) Britton and Rose at the La Selva Biological Station in the Atlantic lo wland rain forest of Costa Rica. The large, night-blooming, unpleasantly-sm elling flowers were suspended on elongated main stems that hang down as muc h as 2 m below canopy tree branches, resulting in a unique form of flagelli flory. The only visitors to flowers were three species of glossophagine bat s: Glossophoga commissarisi, Hylonycteris underwoodi and Lichonycteris obsc ura. Patterns of nectar secretion and concentration were found to be typica l for bat-pollinated flowers. Flowering phenology and the occurrence of pol len on bats were recorded during a l-yr period. Preliminary observations su ggest that at least two other Costa Rican species of Weberocereus, W. bioll eyi and W. trichophorus and possibly other species of the tribe Hylocereeae , are also pollinated by glossophagine bats.