RESUMEN
Lophopterys floribunda is a Neotropical species of Malpighiaceae endemic to Brazil, occurring in both the Amazon and Atlantic Forest. Instead of the typical bi-glandular sepals reported for Neotropical Malpighiaceae, this species presents a single, large gland on the lateral sepals. In addition, ant patrolling was observed at the apex of bracts and bracteoles during fieldwork. Thus, this work aimed to describe the sepalar gland of L. floribunda and other secretory structures in its flowers and inflorescence. Samples of bracts, bracteoles, sepals, petals, and anther were collected and submitted to usual anatomical techniques. Unexpected nectaries at the apex of bracts and bracteoles, not visible to the naked eye, were described and represent a new type of structure for the family due to both their position and size. Mutualistic ants consume the exudate produced by these tiny nectaries, and such structures enable a specific visitation pattern for Lophopterys. Typical epithelial elaiophores occur on the lateral sepals, formed by an invaginated epidermis, which predominantly produce lipid secretion. The petal marginal glands are anatomically similar to the standard type of colleter, which exude mucilaginous substances. The exudate produced by the petal marginal glands was considered to have an additional role of contributing to the maintenance of the closed bud during the beginning of development. The globose epidermal cells containing lipids, proteins, and polysaccharides observed in the connective may be responsible for the typical aroma emitted by these flowers. The diversity of secretory structures reported here has application in both systematic and ecological studies of Malpighiaceae.
RESUMEN
The stereotyped floral morphology of Neotropical Malpighiaceae species-zygomorphic and calyx with oil glands-is correlated with oil-bee pollination. In contrast, the floral trends of the Paleotropical lineages are actinomorphy and lack of calyx glands, probably due to the absence of oil-collecting bees. The Paleotropical genus Acridocarpus is an exception because of its zygomorphic, gland-bearing flowers. Glands throughout Acridocarpus inflorescences were morphoanatomically evaluated to verify the occurrence of patterns related to species and geographic distribution. Herbarium (25 species) and fresh samples of A. longifolius were processed according to standard anatomical techniques. To verify the presence of glucose and protein, strip tests were applied to the exudate. Fresh samples were fixed and submitted to histochemical tests. Based on the occurrence, number and placement of glands, three distribution patterns were recognized on the bracteole and ten on the calyx. Bract, bracteole and sepal glands have a typical nectary structure with a palisade-like epidermis and vascularized parenchyma. Glands were classified as short-stalked, sessile or immersed. Histochemical tests performed on bract and sepal glands of A. longifolius were positive for proteins, polysaccharides and phenolic compounds, and negative for oil compounds. Glucose and protein were detected in the exudate. These results allow us to recognize the glands in Acridocarpus inflorescences as nectaries. This comprehensive morphoanatomical study helps to clarify the correlation between patterns of floral morphology and secretion consumers, as well as to better understand floral evolution in Malpighiaceae across their dispersal events.