No abstract

Cactaceae has many vertebrate-pollinated species, and in the subtribe Cereinae, several genera are indicated as being pollinated by bats. In this subtribe, we observed phenotypic specialization in floral morphological attributes associated with chiropterophily, allowing high precision in the determination of this pollination system. However, in loco pollination records of bats have been confirmed only in a few species. In this context, using a morphological approach, we studied the floral biology of 14 columnar cacti of Cereeae-Cereinae with emphasis on species with chiropterophilous attributes and confirmed the role of bats specialized in nectar consumption as pollinators of these taxa. The studied taxa have similarities in their floral bauplan, observed by analysing the overlap in the floral morphospace. The length and opening of the floral tube are important characteristics for pollen deposition. Approximately 156 visits by bats of the subfamilies Glossophaginae and Lonchophyllinae were observed among the studied taxa. Chiropterophily is the prevalent pollination system among Cereinae, and hereby, we verified this system in five of its genera. There is, however, much variation between diurnal and nocturnal systems within this subtribe, and variation among genera and within species of a given genus may reflect the evolutive pathways, this being worthy of future studies.

No abstract

Nectar is an important floral resource, often representing the only source of water for pollinators in arid environments. We investigated whether successive nectar removal would affect the nectar production dynamics of four Melocactus species growing in the Caatinga domain. Nectar was serially extracted from flowers four times per day at regular 60‐min intervals after anthesis. The cactus species showed a consistent pattern of secretion linked to ornithophily, with no significant responses to successive nectar removal and no reabsorption. Nectar secretion covered the entire period of anthesis, starting at 2:30 p.m. and continuing to 5:30 p.m., with the production of 11–38 μl per flower, with sugar concentrations of 10%–32% (3–16 mg of sugar). Individual flowers produced average amounts of 16.9–3.43 mg of sugar per day, corresponding to energy values of 0.06–0.28 kJ. Sympatric populations produced an average of 150–200 flowers per day. The nectar produced by Melocactus can therefore meet the daily energy needs of hummingbirds, which is of special importance during the dry season, when resources are scarce in the Caatinga.