| Mistletoes are aerial parasitic plants of the sandalwood order (Santalales), composed of ~1,500–۱,۶۰۰ species worldwide (Nickrent et al. 2010). Some temperate European and North-American species are folkloric and mystic, but the beauty of colors and the variety of forms are almost exclusively found in the tropical species in South and Central Americas, Africa, Australia, and New Zealand. Loranthaceae, the showy mistletoes, is the largest family on these continents. Within it, Psittacanthus is one of the most spectacular and species-rich genus (~119 species), occurring from Baja California, Mexico to northern Argentina (Kuijt 2009). The large radiation of species within Psittacanthus has been related to interactions with birds, as the genus is regarded as entirely hummingbird-pollinated and bird-dispersed (Restrepo et al. 2002, Vidal-Russell and Nickrent 2008). Nonetheless, while studying the pollination of Psittacanthus species in the Brazilian Pantanal and Amazon, we found P. acinarius and P. eucalyptifolius to be bat- and bee-pollinated, respectively (Fig. 1). Flower characteristics of these species do not provide cues for hummingbird pollination, such as a narrow and long tubular corolla, absence of odor, and a combination of red, yellow, and orange colors. Instead, P. acinarius has brush flowers that exhale an unpleasant odor and are inconspicuously greenish and P. eucalyptifolius has curved buds and slightly zygomorphic flowers, sweetly scented and vividly yellow. Based on these floral traits, bat pollination in P. acinarius was previously assumed by Araujo and Sazima (2003) and suspected by Kuijt (2009), who also pointed out the potential of bat pollination in P. macrantherus and insect pollination in P. eucalyptifolius. Throughout several years of continuous fieldwork in the region of Pantanal of Miranda (19°۳۴۰ S; 57°۰۰۰ W), we found P. acinarius individuals flowering yearly from January to August (Araujo and Sazima 2003). Each plant produced ~1–۱۰ inflorescences and 10–۱۵۰ buds in total, and opened 1–۲۰ flowers per night. Because its buds and pedicels are thicker, inflorescences are stronger than those of other Psittacanthus species that are pollinated by hummingbirds. P. acinarius flowers open at early evening (18:30–۱۹:۰۰) when the six petals (60 mm length) separate, exposing the central style (55 mm length) with a simple stigma. One stamen is attached to each petal, so the six anthers are peripheral and introrse (dehiscence facing inward). These traits contrast with hummingbird-pollinated Psittacanthus species whose petals often curl in open flowers and stamens are central with extrorse anthers (facing outward). On April 27, 2000, between 19:00 and 20:00, we extracted an average of 15.2 lL of nectar with a mean sugar concentration of 16.5% from each of four flowers of different P. acinarius individuals. This is a sugar concentration expected for bat-pollinated flowers in the Neotropics (Ornelas et al. 2007) |
