Diurnal versus nocturnal pollination success in Billbergia horrida Regel (Bromeliaceae) and the first record of chiropterophily for the genus.

Billbergia horrida is endemic of the Atlantic Forest fragments in southeastern Brazil and characterized by flowers with typical traits for pollination by nocturnal animals. Although the majority of Billbergia species rely on diurnal pollination by hummingbirds, B. horrida is also visited by bats and this study evidences for the first time the occurrence of chiropterophily within the genus. The role of different groups of pollinators on the reproductive success of B. horrida was evaluated, as well as the correlation of nectar features in sustaining these animals during different periods of the day. Bats contributed to 82.1% of fruit set of B. horrida. Hummingbirds, in turn, contributed to only 10% of fruit set, and were poorly related to the reproductive success of this species. Amounts of nectar production and sugar concentration were similar to those of other chiropterophilous bromeliads and only the nectar volume changed significantly throughout the period of flower availability. Recurring visits by hummingbirds were probably because the flowers of B. horrida were open for 24h, offering energetic rewards for daytime visitors and due to the presence of other attractive bromeliad species growing at the same phorophyte and flowering at the same time.